diff --git a/trial/cocago/cocago_builder.go b/trial/cocago/cocago_builder.go
index 570d25eb2f897254c47f9bdc16c72c0f26f7482f..054bcc42a2d4e2f3789fdb0e1976611d3b0b7579 100644
--- a/trial/cocago/cocago_builder.go
+++ b/trial/cocago/cocago_builder.go
@@ -24,7 +24,7 @@ func BuildPropertyField(name string, field *ast.Field) *trial.CodeProperty {
 		case *ast.SelectorExpr:
 			typeName = getSelectorName(*typeX)
 		default:
-			fmt.Println("BuildPropertyField ArrayType", reflect.TypeOf(x.Elt))
+			fmt.Fprintf(output, "BuildPropertyField ArrayType %s\n", reflect.TypeOf(x.Elt))
 		}
 	case *ast.FuncType:
 		typeType = "Function"
@@ -41,7 +41,7 @@ func BuildPropertyField(name string, field *ast.Field) *trial.CodeProperty {
 	case *ast.SelectorExpr:
 		typeName = getSelectorName(*x)
 	default:
-		fmt.Println("BuildPropertyField", reflect.TypeOf(x))
+		fmt.Fprintf(output, "BuildPropertyField %s\n", reflect.TypeOf(x))
 	}
 
 	property := &trial.CodeProperty{
diff --git a/trial/cocago/cocago_parser.go b/trial/cocago/cocago_parser.go
index b57fcbec65fc42bd067e36ab263863e6717d94db..a97c8c25f4aafad85473f0cb2106d6e07eb4ddcf 100644
--- a/trial/cocago/cocago_parser.go
+++ b/trial/cocago/cocago_parser.go
@@ -1,12 +1,15 @@
 package cocago
 
 import (
+	"bytes"
 	"fmt"
 	"github.com/phodal/coca/pkg/domain/trial"
 	"go/ast"
 	"go/parser"
 	"go/token"
+	"io"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"reflect"
 )
@@ -16,16 +19,27 @@ var currentPackage *trial.CodePackage
 type CocagoParser struct {
 }
 
+var debug = false
+var output io.Writer
+
 func NewCocagoParser() *CocagoParser {
 	currentPackage = &trial.CodePackage{}
+	output = os.Stdout
 	return &CocagoParser{}
 }
 
+func (n *CocagoParser) SetOutput(isDebug bool) io.Writer {
+	output = new(bytes.Buffer)
+	debug = isDebug
+
+	return output
+}
+
 func (n *CocagoParser) ProcessFile(fileName string) trial.CodeFile {
 	absPath, _ := filepath.Abs(fileName)
 	content, _ := ioutil.ReadFile(absPath)
 
-	fmt.Println("process file", fileName)
+	fmt.Fprintf(output, "process file %s\n", fileName)
 
 	fset := token.NewFileSet()
 	f, err := parser.ParseFile(fset, fileName, string(content), 0)
@@ -75,7 +89,7 @@ func (n *CocagoParser) Visitor(f *ast.File, fset *token.FileSet, fileName string
 			AddInterface(x, lastIdent, &currentFile)
 		default:
 			if reflect.TypeOf(x) != nil {
-				fmt.Println("Visitor case ", reflect.TypeOf(x))
+				fmt.Fprintf(output, "Visitor case %s\n", reflect.TypeOf(x))
 			}
 		}
 		return true
@@ -146,7 +160,7 @@ func BuildReceiver(x *ast.FuncDecl, recv string) string {
 		case *ast.Ident:
 			recv = x.Name
 		default:
-			fmt.Println("AddFunctionDecl", reflect.TypeOf(x))
+			fmt.Fprintf(output, "AddFunctionDecl %s\n", reflect.TypeOf(x))
 		}
 	}
 	return recv
@@ -157,7 +171,7 @@ func BuildMethodCall(codeFunc *trial.CodeFunction, item ast.Stmt) {
 	case *ast.ExprStmt:
 		BuildMethodCallExprStmt(it, codeFunc)
 	default:
-		fmt.Println("methodCall", reflect.TypeOf(it))
+		fmt.Fprintf(output, "methodCall %s\n", reflect.TypeOf(it))
 	}
 }
 
@@ -206,7 +220,7 @@ func BuildExpr(expr ast.Expr) (string, string) {
 		}
 		return x.Name, name
 	default:
-		fmt.Println("BuildExpr", reflect.TypeOf(x))
+		fmt.Fprintf(output, "BuildExpr %s\n", reflect.TypeOf(x))
 	}
 	return "", ""
 }
@@ -245,4 +259,3 @@ func AddStructType(currentStruct trial.CodeDataStruct, x *ast.StructType, curren
 	currentFile.Members = append(currentFile.Members, &member)
 	currentFile.DataStructures = append(currentFile.DataStructures, currentStruct)
 }
-
diff --git a/trial/cocago/cocago_parser_test.go b/trial/cocago/cocago_parser_test.go
index f4f02c63bfc3160e39db8781b03a3150a3fc9346..5a2d44288079776d896c06dc35c6a7ef73fe4130 100644
--- a/trial/cocago/cocago_parser_test.go
+++ b/trial/cocago/cocago_parser_test.go
@@ -18,6 +18,7 @@ var testParser *CocagoParser
 
 func setup() {
 	testParser = NewCocagoParser()
+	testParser.SetOutput(true)
 }
 
 func shutdown() {
@@ -60,9 +61,8 @@ func TestCocagoParser_ProcessFile(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			n := &CocagoParser{}
 			filePath := getFilePath(tt.fileName)
-			if got := n.ProcessFile(filePath + ".code"); !cocatest.JSONFileBytesEqual(got, filePath+".json") {
+			if got := testParser.ProcessFile(filePath + ".code"); !cocatest.JSONFileBytesEqual(got, filePath+".json") {
 				t.Errorf("ProcessFile() = %v, want %v", got, tt.fileName)
 			}
 		})
diff --git a/trial/pkg/application/processor/process.go b/trial/pkg/application/processor/process.go
index be17f51b57b6e6040a74bc90e4c10aff7bf1beab..b30b6e2d7c0c11298d95240b4d68a439b07039f7 100644
--- a/trial/pkg/application/processor/process.go
+++ b/trial/pkg/application/processor/process.go
@@ -8,7 +8,7 @@ import (
 	"sync"
 )
 
-func ProcessPackage(path string) []*trial.CodeFile {
+func ProcessPackage(path string, debug bool) []*trial.CodeFile {
 	var wg sync.WaitGroup
 
 	var GoFileFilter = func(path string) bool {
@@ -18,6 +18,9 @@ func ProcessPackage(path string) []*trial.CodeFile {
 	files := cocafile.GetFilesWithFilter(path ,GoFileFilter)
 	filesData := make([]*trial.CodeFile, len(files))
 	parser := cocago.NewCocagoParser()
+	if debug {
+		parser.SetOutput(true)
+	}
 	for i, file := range files {
 		wg.Add(1)
 		go func(i int, file string) {
diff --git a/trial/pkg/application/processor/process_test.go b/trial/pkg/application/processor/process_test.go
index 46b18eb12454c5278ad104f0e6f88f4e47e96cc7..f254ef616bd7c7338167303d1d11108139da3db6 100644
--- a/trial/pkg/application/processor/process_test.go
+++ b/trial/pkg/application/processor/process_test.go
@@ -9,6 +9,7 @@ func Test_ProcessPackage(t *testing.T) {
 	t.Parallel()
 	g := NewGomegaWithT(t)
 
-	results := ProcessPackage("../../../../pkg/domain")
+	debug := true
+	results := ProcessPackage("../../../../pkg/domain", debug)
 	g.Expect(len(results)).To(Equal(27))
 }
\ No newline at end of file
diff --git a/trial/tcmd/analysis_go.go b/trial/tcmd/analysis_go.go
index 9226a4caea0e8ec7cc50f2fdcf1dfec772de218a..7c8e7c9abc1ab677c427bada352f594e00ef483a 100644
--- a/trial/tcmd/analysis_go.go
+++ b/trial/tcmd/analysis_go.go
@@ -28,6 +28,7 @@ var analysisGoCmd = &cobra.Command{
 		files := cocafile.GetFilesWithFilter(importPath, cocafile.GoFileFilter)
 		for _, file := range files {
 			parser := cocago.NewCocagoParser()
+			parser.SetOutput(true)
 			result := parser.ProcessFile(file)
 
 			results = append(results, result)