diff --git a/x/token/class/errors.go b/x/token/class/errors.go
deleted file mode 100644
index abf9df9602..0000000000
--- a/x/token/class/errors.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package class
-
-import (
-	sdkerrors "github.com/line/lbm-sdk/types/errors"
-)
-
-const contractCodespace = "contract"
-
-var (
-	ErrInvalidContractID = sdkerrors.Register(contractCodespace, 2, "invalid contractID")
-	ErrContractNotExist  = sdkerrors.Register(contractCodespace, 3, "contract does not exist")
-)
diff --git a/x/token/class/validation.go b/x/token/class/validation.go
index 98bee82d08..073c6e4b79 100644
--- a/x/token/class/validation.go
+++ b/x/token/class/validation.go
@@ -3,6 +3,8 @@ package class
 import (
 	"fmt"
 	"regexp"
+
+	sdkerrors "github.com/line/lbm-sdk/types/errors"
 )
 
 var (
@@ -14,7 +16,7 @@ var (
 // ValidateID returns whether the contract id is valid
 func ValidateID(id string) error {
 	if !reContractID.MatchString(id) {
-		return ErrInvalidContractID.Wrapf("invalid contract id: %s", id)
+		return sdkerrors.ErrInvalidRequest.Wrapf("invalid contract id; %s", id)
 	}
 	return nil
 }
diff --git a/x/token/errors.go b/x/token/errors.go
index a86e5fb8eb..cc285c4872 100644
--- a/x/token/errors.go
+++ b/x/token/errors.go
@@ -7,28 +7,21 @@ import (
 const tokenCodespace = ModuleName
 
 var (
-	ErrTokenExist               = sdkerrors.Register(tokenCodespace, 2, "token already exists")
-	ErrTokenNotExist            = sdkerrors.Register(tokenCodespace, 3, "token does not exist")
-	ErrTokenNotMintable         = sdkerrors.Register(tokenCodespace, 4, "token is not mintable")
-	ErrInvalidTokenName         = sdkerrors.Register(tokenCodespace, 5, "token name should not be empty")
-	ErrInvalidTokenDecimals     = sdkerrors.Register(tokenCodespace, 6, "token decimals should be within the range in 0 ~ 18")
-	ErrInvalidAmount            = sdkerrors.Register(tokenCodespace, 7, "invalid token amount")
-	ErrInvalidImageURILength    = sdkerrors.Register(tokenCodespace, 8, "invalid token uri length")
-	ErrInvalidNameLength        = sdkerrors.Register(tokenCodespace, 9, "invalid name length")
-	ErrInvalidTokenSymbol       = sdkerrors.Register(tokenCodespace, 10, "invalid token symbol")
-	ErrTokenNoPermission        = sdkerrors.Register(tokenCodespace, 11, "account does not have the permission")
-	ErrAccountExist             = sdkerrors.Register(tokenCodespace, 12, "account already exists")
-	ErrAccountNotExist          = sdkerrors.Register(tokenCodespace, 13, "account does not exists")
-	ErrInsufficientBalance      = sdkerrors.Register(tokenCodespace, 14, "insufficient balance")
-	ErrSupplyExist              = sdkerrors.Register(tokenCodespace, 15, "supply for token already exists")
-	ErrInsufficientSupply       = sdkerrors.Register(tokenCodespace, 16, "insufficient supply")
-	ErrInvalidChangesFieldCount = sdkerrors.Register(tokenCodespace, 17, "invalid count of field changes")
-	ErrEmptyChanges             = sdkerrors.Register(tokenCodespace, 18, "changes is empty")
-	ErrInvalidChangesField      = sdkerrors.Register(tokenCodespace, 19, "invalid field of changes")
-	ErrDuplicateChangesField    = sdkerrors.Register(tokenCodespace, 20, "invalid field of changes")
-	ErrInvalidMetaLength        = sdkerrors.Register(tokenCodespace, 21, "invalid meta length")
-	ErrSupplyOverflow           = sdkerrors.Register(tokenCodespace, 22, "supply for token reached maximum")
-	ErrApproverProxySame        = sdkerrors.Register(tokenCodespace, 23, "approver is same with proxy")
-	ErrTokenNotApproved         = sdkerrors.Register(tokenCodespace, 24, "proxy is not approved on the token")
-	ErrTokenAlreadyApproved     = sdkerrors.Register(tokenCodespace, 25, "proxy is already approved on the token")
+	ErrContractNotFound           = sdkerrors.Register(tokenCodespace, 3, "contract not found")
+	ErrNotMintable                = sdkerrors.Register(tokenCodespace, 4, "not mintable")
+	ErrInvalidDecimals            = sdkerrors.Register(tokenCodespace, 6, "invalid decimals")
+	ErrInvalidAmount              = sdkerrors.Register(tokenCodespace, 7, "invalid amount")
+	ErrInvalidImageURI            = sdkerrors.Register(tokenCodespace, 8, "invalid image_uri")
+	ErrInvalidName                = sdkerrors.Register(tokenCodespace, 9, "invalid name")
+	ErrInvalidSymbol              = sdkerrors.Register(tokenCodespace, 10, "invalid symbol")
+	ErrGrantNotFound              = sdkerrors.Register(tokenCodespace, 11, "grant not found")
+	ErrInsufficientTokens         = sdkerrors.Register(tokenCodespace, 14, "insufficient tokens")
+	ErrInvalidChanges             = sdkerrors.Register(tokenCodespace, 17, "invalid changes")
+	ErrInvalidMeta                = sdkerrors.Register(tokenCodespace, 21, "invalid meta")
+	ErrOperatorIsHolder           = sdkerrors.Register(tokenCodespace, 23, "operator and holder should be different")
+	ErrAuthorizationNotFound      = sdkerrors.Register(tokenCodespace, 24, "authorization not found")
+	ErrAuthorizationAlreadyExists = sdkerrors.Register(tokenCodespace, 25, "authorization already exists")
+	ErrInvalidPermission          = sdkerrors.Register(tokenCodespace, 26, "invalid permission")
+	ErrGrantAlreadyExists         = sdkerrors.Register(tokenCodespace, 27, "grant already exists")
+	ErrInvalidContractID          = sdkerrors.Register(tokenCodespace, 28, "invalid contract id")
 )
diff --git a/x/token/keeper/msg_server.go b/x/token/keeper/msg_server.go
index 3d7213cfba..638e407df1 100644
--- a/x/token/keeper/msg_server.go
+++ b/x/token/keeper/msg_server.go
@@ -4,7 +4,6 @@ import (
 	"context"
 
 	sdk "github.com/line/lbm-sdk/types"
-	sdkerrors "github.com/line/lbm-sdk/types/errors"
 	"github.com/line/lbm-sdk/x/token"
 )
 
@@ -57,7 +56,7 @@ func (s msgServer) TransferFrom(c context.Context, req *token.MsgTransferFrom) (
 	to := sdk.MustAccAddressFromBech32(req.To)
 
 	if _, err := s.keeper.GetAuthorization(ctx, req.ContractId, from, proxy); err != nil {
-		return nil, token.ErrTokenNotApproved.Wrap(err.Error())
+		return nil, err
 	}
 
 	if err := s.keeper.Send(ctx, req.ContractId, from, to, req.Amount); err != nil {
@@ -154,10 +153,10 @@ func (s msgServer) GrantPermission(c context.Context, req *token.MsgGrantPermiss
 	grantee := sdk.MustAccAddressFromBech32(req.To)
 	permission := token.Permission(token.LegacyPermissionFromString(req.Permission))
 	if _, err := s.keeper.GetGrant(ctx, req.ContractId, granter, permission); err != nil {
-		return nil, token.ErrTokenNoPermission.Wrap(err.Error())
+		return nil, err
 	}
 	if _, err := s.keeper.GetGrant(ctx, req.ContractId, grantee, permission); err == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrapf("%s is already granted for %s", grantee, permission)
+		return nil, token.ErrGrantAlreadyExists.Wrapf("%s already granted for %s", grantee, permission)
 	}
 
 	s.keeper.Grant(ctx, req.ContractId, granter, grantee, permission)
@@ -180,7 +179,7 @@ func (s msgServer) RevokePermission(c context.Context, req *token.MsgRevokePermi
 	grantee := sdk.MustAccAddressFromBech32(req.From)
 	permission := token.Permission(token.LegacyPermissionFromString(req.Permission))
 	if _, err := s.keeper.GetGrant(ctx, req.ContractId, grantee, permission); err != nil {
-		return nil, token.ErrTokenNoPermission.Wrap(err.Error())
+		return nil, err
 	}
 
 	s.keeper.Abandon(ctx, req.ContractId, grantee, permission)
@@ -242,7 +241,7 @@ func (s msgServer) Modify(c context.Context, req *token.MsgModify) (*token.MsgMo
 	grantee := sdk.MustAccAddressFromBech32(req.Owner)
 
 	if _, err := s.keeper.GetGrant(ctx, req.ContractId, grantee, token.PermissionModify); err != nil {
-		return nil, token.ErrTokenNoPermission.Wrap(err.Error())
+		return nil, err
 	}
 
 	if err := s.keeper.Modify(ctx, req.ContractId, grantee, req.Changes); err != nil {
diff --git a/x/token/keeper/send.go b/x/token/keeper/send.go
index ede12e8e33..f3a3b95633 100644
--- a/x/token/keeper/send.go
+++ b/x/token/keeper/send.go
@@ -2,13 +2,12 @@ package keeper
 
 import (
 	sdk "github.com/line/lbm-sdk/types"
-	sdkerrors "github.com/line/lbm-sdk/types/errors"
 	"github.com/line/lbm-sdk/x/token"
 )
 
 func (k Keeper) Send(ctx sdk.Context, contractID string, from, to sdk.AccAddress, amount sdk.Int) error {
 	if !amount.IsPositive() {
-		panic(sdkerrors.ErrInvalidRequest.Wrap("amount must be positive"))
+		panic(token.ErrInvalidAmount.Wrap("amount must be positive"))
 	}
 
 	if err := k.subtractToken(ctx, contractID, from, amount); err != nil {
@@ -24,7 +23,7 @@ func (k Keeper) AuthorizeOperator(ctx sdk.Context, contractID string, holder, op
 		return err
 	}
 	if _, err := k.GetAuthorization(ctx, contractID, holder, operator); err == nil {
-		return token.ErrTokenAlreadyApproved.Wrap("Already authorized")
+		return token.ErrAuthorizationAlreadyExists.Wrapf("%s already authorized by %s", operator, holder)
 	}
 
 	k.setAuthorization(ctx, contractID, holder, operator)
@@ -56,7 +55,7 @@ func (k Keeper) GetAuthorization(ctx sdk.Context, contractID string, holder, ope
 			Operator: operator.String(),
 		}, nil
 	}
-	return nil, sdkerrors.ErrNotFound.Wrapf("no authorization to %s by %s", operator, holder)
+	return nil, token.ErrAuthorizationNotFound.Wrapf("%s not authorized by %s", operator, holder)
 }
 
 func (k Keeper) setAuthorization(ctx sdk.Context, contractID string, holder, operator sdk.AccAddress) {
@@ -75,8 +74,7 @@ func (k Keeper) subtractToken(ctx sdk.Context, contractID string, addr sdk.AccAd
 	balance := k.GetBalance(ctx, contractID, addr)
 	newBalance := balance.Sub(amount)
 	if newBalance.IsNegative() {
-		// Daphne emits ErrInsufficientFunds here, which is against to the spec.
-		return token.ErrInsufficientBalance.Wrapf("%s is smaller than %s", balance, amount)
+		return token.ErrInsufficientTokens.Wrapf("%s is smaller than %s", balance, amount)
 	}
 
 	k.setBalance(ctx, contractID, addr, newBalance)
diff --git a/x/token/keeper/supply.go b/x/token/keeper/supply.go
index 64e2521fc5..1fcd463241 100644
--- a/x/token/keeper/supply.go
+++ b/x/token/keeper/supply.go
@@ -69,7 +69,7 @@ func (k Keeper) GetClass(ctx sdk.Context, contractID string) (*token.TokenClass,
 	store := ctx.KVStore(k.storeKey)
 	bz := store.Get(classKey(contractID))
 	if bz == nil {
-		return nil, token.ErrTokenNotExist.Wrapf("no class for %s", contractID)
+		return nil, token.ErrContractNotFound.Wrap(contractID)
 	}
 
 	var class token.TokenClass
@@ -110,7 +110,7 @@ func (k Keeper) Mint(ctx sdk.Context, contractID string, grantee, to sdk.AccAddr
 
 func (k Keeper) mint(ctx sdk.Context, contractID string, grantee, to sdk.AccAddress, amount sdk.Int) error {
 	if _, err := k.GetGrant(ctx, contractID, grantee, token.PermissionMint); err != nil {
-		return token.ErrTokenNoPermission.Wrap(err.Error())
+		return err
 	}
 
 	k.mintToken(ctx, contractID, to, amount)
@@ -150,7 +150,7 @@ func (k Keeper) Burn(ctx sdk.Context, contractID string, from sdk.AccAddress, am
 
 func (k Keeper) burn(ctx sdk.Context, contractID string, from sdk.AccAddress, amount sdk.Int) error {
 	if _, err := k.GetGrant(ctx, contractID, from, token.PermissionBurn); err != nil {
-		return token.ErrTokenNoPermission.Wrap(err.Error())
+		return err
 	}
 
 	if err := k.burnToken(ctx, contractID, from, amount); err != nil {
@@ -181,10 +181,10 @@ func (k Keeper) OperatorBurn(ctx sdk.Context, contractID string, operator, from
 func (k Keeper) operatorBurn(ctx sdk.Context, contractID string, operator, from sdk.AccAddress, amount sdk.Int) error {
 	_, err := k.GetGrant(ctx, contractID, operator, token.PermissionBurn)
 	if err != nil {
-		return token.ErrTokenNoPermission.Wrap(err.Error())
+		return err
 	}
 	if _, err := k.GetAuthorization(ctx, contractID, from, operator); err != nil {
-		return token.ErrTokenNotApproved.Wrap(err.Error())
+		return err
 	}
 
 	if err := k.burnToken(ctx, contractID, from, amount); err != nil {
@@ -354,7 +354,7 @@ func (k Keeper) GetGrant(ctx sdk.Context, contractID string, grantee sdk.AccAddr
 		return grant, nil
 	}
 
-	return nil, sdkerrors.ErrNotFound.Wrapf("%s has no %s permission", grantee, permission)
+	return nil, token.ErrGrantNotFound.Wrapf("%s has no %s", grantee, permission)
 }
 
 func (k Keeper) setGrant(ctx sdk.Context, contractID string, grantee sdk.AccAddress, permission token.Permission) {
diff --git a/x/token/msgs.go b/x/token/msgs.go
index 6e1fab6f77..a04d9fc647 100644
--- a/x/token/msgs.go
+++ b/x/token/msgs.go
@@ -21,7 +21,6 @@ func (m MsgSend) ValidateBasic() error {
 	}
 
 	if err := validateAmount(m.Amount); err != nil {
-		// Daphne emits ErrInvalidCoins here, which is against to the spec.
 		return err
 	}
 
@@ -455,7 +454,7 @@ func (m MsgModify) ValidateBasic() error {
 	checkedFields := map[string]bool{}
 	for _, change := range m.Changes {
 		if checkedFields[change.Field] {
-			return ErrDuplicateChangesField.Wrapf("duplicate fields: %s", change.Field)
+			return ErrInvalidChanges.Wrapf("duplicate key: %s", change.Field)
 		}
 		checkedFields[change.Field] = true
 
@@ -464,7 +463,7 @@ func (m MsgModify) ValidateBasic() error {
 		}
 	}
 	if len(checkedFields) == 0 {
-		return ErrEmptyChanges.Wrapf("no field provided")
+		return ErrInvalidChanges.Wrapf("no field provided")
 	}
 
 	return nil
diff --git a/x/token/validation.go b/x/token/validation.go
index 258c8bc2fb..84f8fa2a95 100644
--- a/x/token/validation.go
+++ b/x/token/validation.go
@@ -6,7 +6,6 @@ import (
 	"unicode/utf8"
 
 	sdk "github.com/line/lbm-sdk/types"
-	sdkerrors "github.com/line/lbm-sdk/types/errors"
 	"github.com/line/lbm-sdk/x/token/class"
 )
 
@@ -27,44 +26,44 @@ func stringInSize(str string, size int) bool {
 
 func validateName(name string) error {
 	if len(name) == 0 {
-		return ErrInvalidTokenName.Wrap("name cannot be empty")
+		return ErrInvalidName.Wrap("cannot be empty")
 	} else if !stringInSize(name, maxName) {
-		return ErrInvalidNameLength.Wrapf("name cannot be longer than %d", maxName)
+		return ErrInvalidName.Wrapf("cannot be longer than %d", maxName)
 	}
 	return nil
 }
 
 func validateSymbol(symbol string) error {
 	if !reSymbol.MatchString(symbol) {
-		return ErrInvalidTokenSymbol.Wrapf("invalid symbol: %s, valid expression is: %s", symbol, reSymbolString)
+		return ErrInvalidSymbol.Wrapf("got; %s, valid expression is; %s", symbol, reSymbolString)
 	}
 	return nil
 }
 
 func validateImageURI(uri string) error {
 	if !stringInSize(uri, maxImageURI) {
-		return ErrInvalidImageURILength.Wrapf("image_uri cannot be longer than %d", maxImageURI)
+		return ErrInvalidImageURI.Wrapf("cannot be longer than %d", maxImageURI)
 	}
 	return nil
 }
 
 func validateMeta(meta string) error {
 	if !stringInSize(meta, maxMeta) {
-		return ErrInvalidMetaLength.Wrapf("meta cannot be longer than %d", maxMeta)
+		return ErrInvalidMeta.Wrapf("cannot be longer than %d", maxMeta)
 	}
 	return nil
 }
 
 func validateDecimals(decimals int32) error {
 	if decimals < 0 || decimals > 18 {
-		return ErrInvalidTokenDecimals.Wrapf("invalid decimals: %d", decimals)
+		return ErrInvalidDecimals.Wrapf("must be >=0 and <18, got; %d", decimals)
 	}
 	return nil
 }
 
 func validateAmount(amount sdk.Int) error {
 	if !amount.IsPositive() {
-		return ErrInvalidAmount.Wrapf("amount must be positive: %s", amount)
+		return ErrInvalidAmount.Wrapf("must be positive: %s", amount)
 	}
 	return nil
 }
@@ -75,7 +74,7 @@ func validateLegacyPermission(permission string) error {
 
 func ValidatePermission(permission Permission) error {
 	if p := Permission_value[Permission_name[int32(permission)]]; p == 0 {
-		return sdkerrors.ErrInvalidPermission.Wrapf("invalid permission: %s", permission)
+		return ErrInvalidPermission.Wrap(permission.String())
 	}
 	return nil
 }
@@ -89,11 +88,15 @@ func validateChange(change Pair) error {
 
 	validator, ok := validators[change.Field]
 	if !ok {
-		return ErrInvalidChangesField.Wrapf("invalid field: %s", change.Field)
+		return ErrInvalidChanges.Wrapf("invalid key: %s", change.Field)
 	}
 	return validator(change.Value)
 }
 
 func ValidateContractID(id string) error {
-	return class.ValidateID(id)
+	if err := class.ValidateID(id); err != nil {
+		return ErrInvalidContractID.Wrap(id)
+	}
+
+	return nil
 }