diff --git a/lib/block/operation.go b/lib/block/operation.go
index 6275fed14..639a412ea 100644
--- a/lib/block/operation.go
+++ b/lib/block/operation.go
@@ -1,6 +1,7 @@
 package block
 
 import (
+	"encoding/json"
 	"fmt"
 
 	"boscoin.io/sebak/lib/common"
@@ -42,7 +43,7 @@ func NewBlockOperationKey(opHash, txHash string) string {
 }
 
 func NewBlockOperationFromOperation(op operation.Operation, tx transaction.Transaction, blockHeight uint64, opIndex int) (BlockOperation, error) {
-	body, err := op.B.Serialize()
+	body, err := json.Marshal(op.B)
 	if err != nil {
 		return BlockOperation{}, err
 	}
diff --git a/lib/block/operation_test.go b/lib/block/operation_test.go
index c522e9b2c..fa06ff67d 100644
--- a/lib/block/operation_test.go
+++ b/lib/block/operation_test.go
@@ -22,8 +22,7 @@ func TestNewBlockOperationFromOperation(t *testing.T) {
 	require.Equal(t, bo.Type, op.H.Type)
 	require.Equal(t, bo.TxHash, tx.H.Hash)
 	require.Equal(t, bo.Source, tx.B.Source)
-	encoded, err := op.B.Serialize()
-	require.NoError(t, err)
+	encoded := common.MustMarshalJSON(op.B)
 	require.Equal(t, bo.Body, encoded)
 }
 
@@ -125,8 +124,7 @@ func TestBlockOperationSaveByTransaction(t *testing.T) {
 		require.Equal(t, bo.Type, op.H.Type)
 		require.Equal(t, bo.TxHash, tx.H.Hash)
 		require.Equal(t, bo.Source, tx.B.Source)
-		encoded, err := op.B.Serialize()
-		require.NoError(t, err)
+		encoded := common.MustMarshalJSON(op.B)
 		require.Equal(t, bo.Body, encoded)
 	}
 }
diff --git a/lib/transaction/operation/collect_tx_fee.go b/lib/transaction/operation/collect_tx_fee.go
index 77ae236df..bf3b30638 100644
--- a/lib/transaction/operation/collect_tx_fee.go
+++ b/lib/transaction/operation/collect_tx_fee.go
@@ -1,8 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
-
 	"boscoin.io/sebak/lib/common"
 	"boscoin.io/sebak/lib/common/keypair"
 	"boscoin.io/sebak/lib/errors"
@@ -72,10 +70,6 @@ func (o CollectTxFee) GetAmount() common.Amount {
 	return o.Amount
 }
 
-func (o CollectTxFee) Serialize() (encoded []byte, err error) {
-	return json.Marshal(o)
-}
-
 func (o CollectTxFee) HasFee() bool {
 	return false
 }
diff --git a/lib/transaction/operation/congress_voting.go b/lib/transaction/operation/congress_voting.go
index bda154d71..210d3ffb8 100644
--- a/lib/transaction/operation/congress_voting.go
+++ b/lib/transaction/operation/congress_voting.go
@@ -1,8 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
-
 	"boscoin.io/sebak/lib/common"
 	"boscoin.io/sebak/lib/errors"
 )
@@ -33,10 +31,6 @@ func NewCongressVoting(contract string, start, end uint64, amount common.Amount,
 	}
 }
 
-func (o CongressVoting) Serialize() (encoded []byte, err error) {
-	encoded, err = json.Marshal(o)
-	return
-}
 func (o CongressVoting) IsWellFormed(common.Config) (err error) {
 	if len(o.Contract) == 0 {
 		return errors.OperationBodyInsufficient
diff --git a/lib/transaction/operation/congress_voting_result.go b/lib/transaction/operation/congress_voting_result.go
index c76a3cb09..0d489b58c 100644
--- a/lib/transaction/operation/congress_voting_result.go
+++ b/lib/transaction/operation/congress_voting_result.go
@@ -1,7 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
 	"strconv"
 	"strings"
 
@@ -61,9 +60,6 @@ func NewCongressVotingResult(
 	}
 }
 
-func (o CongressVotingResult) Serialize() (encoded []byte, err error) {
-	return json.Marshal(o)
-}
 func (o CongressVotingResult) IsWellFormed(common.Config) (err error) {
 	if len(o.BallotStamps.Hash) == 0 {
 		return errors.OperationBodyInsufficient
diff --git a/lib/transaction/operation/create_account.go b/lib/transaction/operation/create_account.go
index 8c76f20ba..ee044e74e 100644
--- a/lib/transaction/operation/create_account.go
+++ b/lib/transaction/operation/create_account.go
@@ -1,8 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
-
 	"boscoin.io/sebak/lib/common"
 	"boscoin.io/sebak/lib/common/keypair"
 	"boscoin.io/sebak/lib/errors"
@@ -22,10 +20,6 @@ func NewCreateAccount(target string, amount common.Amount, linked string) Create
 	}
 }
 
-func (o CreateAccount) Serialize() (encoded []byte, err error) {
-	return json.Marshal(o)
-}
-
 // Implement transaction/operation : IsWellFormed
 func (o CreateAccount) IsWellFormed(common.Config) (err error) {
 	if _, err = keypair.Parse(o.Target); err != nil {
diff --git a/lib/transaction/operation/inflation.go b/lib/transaction/operation/inflation.go
index 3a403f912..d0bc56818 100644
--- a/lib/transaction/operation/inflation.go
+++ b/lib/transaction/operation/inflation.go
@@ -1,7 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
 	"strings"
 
 	"boscoin.io/sebak/lib/common"
@@ -79,10 +78,6 @@ func (o Inflation) GetAmount() common.Amount {
 	return o.Amount
 }
 
-func (o Inflation) Serialize() (encoded []byte, err error) {
-	return json.Marshal(o)
-}
-
 func (o Inflation) HasFee() bool {
 	return false
 }
diff --git a/lib/transaction/operation/inflation_pf.go b/lib/transaction/operation/inflation_pf.go
index f35aaf47c..0af04866c 100644
--- a/lib/transaction/operation/inflation_pf.go
+++ b/lib/transaction/operation/inflation_pf.go
@@ -1,7 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
 	"strconv"
 	"strings"
 
@@ -52,10 +51,6 @@ func (o InflationPF) GetAmount() common.Amount {
 	return o.Amount
 }
 
-func (o InflationPF) Serialize() (encoded []byte, err error) {
-	return json.Marshal(o)
-}
-
 func (o InflationPF) HasFee() bool {
 	return false
 }
diff --git a/lib/transaction/operation/operation.go b/lib/transaction/operation/operation.go
index ffceddb90..b73a0be84 100644
--- a/lib/transaction/operation/operation.go
+++ b/lib/transaction/operation/operation.go
@@ -99,7 +99,6 @@ type Body interface {
 	//   An `error` if that transaction is invalid, `nil` otherwise
 	//
 	IsWellFormed(common.Config) error
-	Serialize() ([]byte, error)
 	HasFee() bool
 }
 
@@ -125,10 +124,6 @@ func (o Operation) IsWellFormed(conf common.Config) (err error) {
 	return o.B.IsWellFormed(conf)
 }
 
-func (o Operation) Serialize() (encoded []byte, err error) {
-	return json.Marshal(o)
-}
-
 func (o Operation) String() string {
 	encoded, _ := json.MarshalIndent(o, "", "  ")
 
diff --git a/lib/transaction/operation/operation_test.go b/lib/transaction/operation/operation_test.go
index 381a81a94..0e626ecbb 100644
--- a/lib/transaction/operation/operation_test.go
+++ b/lib/transaction/operation/operation_test.go
@@ -46,12 +46,11 @@ func TestIsWellFormedOperationLowerAmount(t *testing.T) {
 
 func TestSerializeOperation(t *testing.T) {
 	op := MakeTestPayment(-1)
-	b, err := op.Serialize()
-	require.NoError(t, err)
+	b := common.MustMarshalJSON(op)
 	require.Equal(t, len(b) > 0, true)
 
 	var o Operation
-	err = json.Unmarshal(b, &o)
+	err := json.Unmarshal(b, &o)
 	require.NoError(t, err)
 }
 
diff --git a/lib/transaction/operation/payment.go b/lib/transaction/operation/payment.go
index 97f4c286b..230f0a6c7 100644
--- a/lib/transaction/operation/payment.go
+++ b/lib/transaction/operation/payment.go
@@ -1,8 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
-
 	"boscoin.io/sebak/lib/common"
 	"boscoin.io/sebak/lib/common/keypair"
 	"boscoin.io/sebak/lib/errors"
@@ -20,10 +18,6 @@ func NewPayment(target string, amount common.Amount) Payment {
 	}
 }
 
-func (o Payment) Serialize() (encoded []byte, err error) {
-	return json.Marshal(o)
-}
-
 // Implement transaction/operation : IsWellFormed
 func (o Payment) IsWellFormed(common.Config) (err error) {
 	if _, err = keypair.Parse(o.Target); err != nil {
diff --git a/lib/transaction/operation/unfreezing_request.go b/lib/transaction/operation/unfreezing_request.go
index 474c866c9..1da0f11eb 100644
--- a/lib/transaction/operation/unfreezing_request.go
+++ b/lib/transaction/operation/unfreezing_request.go
@@ -1,8 +1,6 @@
 package operation
 
 import (
-	"encoding/json"
-
 	"boscoin.io/sebak/lib/common"
 )
 
@@ -12,11 +10,6 @@ func NewUnfreezeRequest() UnfreezeRequest {
 	return UnfreezeRequest{}
 }
 
-func (o UnfreezeRequest) Serialize() (encoded []byte, err error) {
-	encoded, err = json.Marshal(o)
-	return
-}
-
 func (o UnfreezeRequest) IsWellFormed(common.Config) (err error) {
 	return
 }