diff --git a/internal/dic/udic.go b/internal/dic/udic.go
index 7ef2c70c..55d1cd77 100644
--- a/internal/dic/udic.go
+++ b/internal/dic/udic.go
@@ -35,11 +35,11 @@ type UserDic struct {
 	Contents []UserDicContent
 }
 
+// UserDicColumnSize is the column size of the user dictionary.
+const UserDicColumnSize = 4
+
 // NewUserDic build a user dictionary from a file.
 func NewUserDic(path string) (udic *UserDic, err error) {
-	const (
-		userDicColumnSize = 4
-	)
 	udic = new(UserDic)
 	f, err := os.Open(path)
 	if err != nil {
@@ -66,7 +66,7 @@ func NewUserDic(path string) (udic *UserDic, err error) {
 	var keys []string
 	for _, line := range text {
 		record := strings.Split(line, ",")
-		if len(record) != userDicColumnSize {
+		if len(record) != UserDicColumnSize {
 			err = fmt.Errorf("invalid format: %s", line)
 			return
 		}
diff --git a/tokenizer/dic.go b/tokenizer/dic.go
index 58dea6ba..b2588112 100644
--- a/tokenizer/dic.go
+++ b/tokenizer/dic.go
@@ -21,11 +21,6 @@ type Dic struct {
 	dic *dic.Dic
 }
 
-// UserDic represents a user dictionary.
-type UserDic struct {
-	dic *dic.UserDic
-}
-
 // SysDic returns the system dictionary (IPA dictionary).
 func SysDic() Dic {
 	return Dic{dic.SysDic()}
@@ -46,9 +41,3 @@ func NewDic(path string) (Dic, error) {
 	d, err := dic.Load(path)
 	return Dic{d}, err
 }
-
-// NewUserDic build a user dictionary from a file.
-func NewUserDic(path string) (UserDic, error) {
-	d, err := dic.NewUserDic(path)
-	return UserDic{d}, err
-}
diff --git a/tokenizer/udic.go b/tokenizer/udic.go
new file mode 100644
index 00000000..fe99630d
--- /dev/null
+++ b/tokenizer/udic.go
@@ -0,0 +1,127 @@
+// Copyright 2016 ikawaha
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// 	You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tokenizer
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strings"
+
+	"github.com/ikawaha/kagome/internal/dic"
+)
+
+// UserDic represents a user dictionary.
+type UserDic struct {
+	dic *dic.UserDic
+}
+
+// NewUserDic build a user dictionary from a file.
+func NewUserDic(path string) (UserDic, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return UserDic{}, err
+	}
+	defer f.Close()
+
+	r, err := NewUserDicRecords(f)
+	if err != nil {
+		return UserDic{}, err
+	}
+	return r.NewUserDic()
+}
+
+// UserDicRecord represents a record of the user dictionary file format.
+type UserDicRecord struct {
+	Text   string   `json:"text"`
+	Tokens []string `json:"tokens"`
+	Yomi   []string `json:"yomi"`
+	Pos    string   `json:"pos"`
+}
+
+// UserDicRecords represents user dictionary data.
+type UserDicRecords []UserDicRecord
+
+func (u UserDicRecords) Len() int           { return len(u) }
+func (u UserDicRecords) Swap(i, j int)      { u[i], u[j] = u[j], u[i] }
+func (u UserDicRecords) Less(i, j int) bool { return u[i].Text < u[j].Text }
+
+// NewUserDicRecords loads user dictionary data from io.Reader.
+func NewUserDicRecords(r io.Reader) (UserDicRecords, error) {
+	var text []string
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		text = append(text, line)
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	var records UserDicRecords
+	for _, line := range text {
+		vec := strings.Split(line, ",")
+		if len(vec) != dic.UserDicColumnSize {
+			return nil, fmt.Errorf("invalid format: %s", line)
+		}
+		tokens := strings.Split(vec[1], " ")
+		yomi := strings.Split(vec[2], " ")
+		if len(tokens) == 0 || len(tokens) != len(yomi) {
+			return nil, fmt.Errorf("invalid format: %s", line)
+		}
+		r := UserDicRecord{
+			Text:   vec[0],
+			Tokens: tokens,
+			Yomi:   yomi,
+			Pos:    vec[3],
+		}
+		records = append(records, r)
+	}
+	return records, nil
+}
+
+// NewUserDic builds a user dictionary.
+func (u UserDicRecords) NewUserDic() (UserDic, error) {
+	udic := new(dic.UserDic)
+	sort.Sort(u)
+
+	prev := ""
+	keys := make([]string, 0, len(u))
+	for _, r := range u {
+		k := strings.TrimSpace(r.Text)
+		if prev == k {
+			return UserDic{}, fmt.Errorf("duplicated error, %+v", r)
+		}
+		prev = k
+		keys = append(keys, k)
+		if len(r.Tokens) == 0 || len(r.Tokens) != len(r.Yomi) {
+			return UserDic{}, fmt.Errorf("invalid format, %+v", r)
+		}
+		c := dic.UserDicContent{
+			Tokens: r.Tokens,
+			Yomi:   r.Yomi,
+			Pos:    r.Pos,
+		}
+		udic.Contents = append(udic.Contents, c)
+	}
+	idx, err := dic.BuildIndexTable(keys)
+	udic.Index = idx
+	return UserDic{dic: udic}, err
+}
diff --git a/tokenizer/udic_test.go b/tokenizer/udic_test.go
new file mode 100644
index 00000000..483fc84c
--- /dev/null
+++ b/tokenizer/udic_test.go
@@ -0,0 +1,189 @@
+// Copyright 2015 ikawaha
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// 	You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tokenizer
+
+import (
+	"encoding/json"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+var testFile = "../_sample/userdic.txt"
+
+func TestNewUserDic01(t *testing.T) {
+	if _, e := NewUserDic(""); e == nil {
+		t.Error("expected error, but no occured\n")
+	}
+}
+
+func TestNewUserDicIndex01(t *testing.T) {
+	udic, e := NewUserDic(testFile)
+	if e != nil {
+		t.Fatalf("unexpected error: %v\n", e)
+	}
+	type tuple struct {
+		inp string
+		id  int
+		ok  bool
+	}
+	callAndRespose := []tuple{
+		tuple{inp: "日本経済新聞", id: 0, ok: true},
+		tuple{inp: "朝青龍", id: 1, ok: true},
+		tuple{inp: "関西国際空港", id: 2, ok: true},
+		tuple{inp: "成田国際空港", id: 9, ok: false},
+	}
+	for _, cr := range callAndRespose {
+		if ids := udic.dic.Index.Search(cr.inp); (len(ids) != 0) != cr.ok {
+			t.Errorf("got %v, expected %v\n", ids, cr.ok)
+		}
+	}
+}
+
+func TestNewUserDicRecords01(t *testing.T) {
+	r := UserDicRecords{
+		{
+			Text:   "日本経済新聞",
+			Tokens: []string{"日本", "経済", "新聞"},
+			Yomi:   []string{"ニホン", "ケイザイ", "シンブン"},
+			Pos:    "カスタム名詞",
+		},
+		{
+			Text:   "朝青龍",
+			Tokens: []string{"朝青龍"},
+			Yomi:   []string{"アサショウリュウ"},
+			Pos:    "カスタム人名",
+		},
+	}
+	udic, err := r.NewUserDic()
+	if err != nil {
+		t.Fatalf("user dic build error, %v", err)
+	}
+	if ids := udic.dic.Index.Search("日本経済新聞"); len(ids) != 1 {
+		t.Errorf("user dic search failed")
+	} else if !reflect.DeepEqual(udic.dic.Contents[ids[0]].Tokens, []string{"日本", "経済", "新聞"}) {
+		t.Errorf("got %+v, expected %+v", udic.dic.Contents[ids[0]].Tokens, []string{"日本", "経済", "新聞"})
+	}
+	if ids := udic.dic.Index.Search("関西国際空港"); len(ids) != 0 {
+		t.Errorf("user dic build failed")
+	}
+	if ids := udic.dic.Index.Search("朝青龍"); len(ids) == 0 {
+		t.Errorf("user dic search failed")
+	} else if !reflect.DeepEqual(udic.dic.Contents[ids[0]].Tokens, []string{"朝青龍"}) {
+		t.Errorf("got %+v, expected %+v", udic.dic.Contents[ids[0]].Tokens, []string{"朝青龍"})
+	}
+}
+
+func TestNewUserDicRecords02(t *testing.T) {
+	s := `
+日本経済新聞,日本 経済 新聞,ニホン ケイザイ シンブン,カスタム名詞
+# 関西国際空港,関西 国際 空港,カンサイ コクサイ クウコウ,カスタム地名
+朝青龍,朝青龍,アサショウリュウ,カスタム人名
+`
+	r := strings.NewReader(s)
+	rec, err := NewUserDicRecords(r)
+	if err != nil {
+		t.Fatalf("user dic build error, %v", err)
+	}
+	udic, err := rec.NewUserDic()
+	if err != nil {
+		t.Fatalf("user dic build error, %v", err)
+	}
+	if ids := udic.dic.Index.Search("日本経済新聞"); len(ids) != 1 {
+		t.Errorf("user dic search failed")
+	} else if !reflect.DeepEqual(udic.dic.Contents[ids[0]].Tokens, []string{"日本", "経済", "新聞"}) {
+		t.Errorf("got %+v, expected %+v", udic.dic.Contents[ids[0]].Tokens, []string{"日本", "経済", "新聞"})
+	}
+	if ids := udic.dic.Index.Search("関西国際空港"); len(ids) != 0 {
+		t.Errorf("user dic build failed")
+	}
+	if ids := udic.dic.Index.Search("朝青龍"); len(ids) == 0 {
+		t.Errorf("user dic search failed")
+	} else if !reflect.DeepEqual(udic.dic.Contents[ids[0]].Tokens, []string{"朝青龍"}) {
+		t.Errorf("got %+v, expected %+v", udic.dic.Contents[ids[0]].Tokens, []string{"朝青龍"})
+	}
+
+}
+
+func TestNewUserDicRecords03(t *testing.T) {
+	r := UserDicRecords{
+		{
+			Text:   "日本経済新聞",
+			Tokens: []string{"日本", "経済", "新聞"},
+			Yomi:   []string{"ニホン", "ケイザイ"},
+			Pos:    "カスタム名詞",
+		},
+	}
+	_, err := r.NewUserDic()
+	if err == nil {
+		t.Errorf("expected error, but nil")
+	}
+}
+
+func TestNewUserDicRecords04(t *testing.T) {
+	r := UserDicRecords{
+		{
+			Text:   "日本経済新聞",
+			Tokens: []string{"日本", "経済", "新聞"},
+			Yomi:   []string{"ニホン", "ケイザイ", "シンブン"},
+			Pos:    "カスタム名詞",
+		},
+		{
+			Text:   "日本経済新聞",
+			Tokens: []string{"日本", "経済", "新聞"},
+			Yomi:   []string{"ニホン", "ケイザイ", "シンブン"},
+			Pos:    "カスタム名詞",
+		},
+	}
+	_, err := r.NewUserDic()
+	if err == nil {
+		t.Errorf("expected error, but nil")
+	}
+}
+
+func TestUserDicRecordsLoadFromJSON(t *testing.T) {
+	var rec UserDicRecords
+	_ = json.Unmarshal([]byte(`[
+        {
+            "text":"日本経済新聞",
+            "tokens":["日本","経済","新聞"],
+            "yomi":["ニホン","ケイザイ","シンブン"],
+            "pos":"カスタム名詞"
+        },
+        {
+            "text":"朝青龍",
+            "tokens":["朝青龍"],
+            "yomi":["アサショウリュウ"],
+            "pos":"カスタム人名"
+        }]`), &rec)
+	expected := UserDicRecords{
+		{
+			Text:   "日本経済新聞",
+			Tokens: []string{"日本", "経済", "新聞"},
+			Yomi:   []string{"ニホン", "ケイザイ", "シンブン"},
+			Pos:    "カスタム名詞",
+		},
+		{
+			Text:   "朝青龍",
+			Tokens: []string{"朝青龍"},
+			Yomi:   []string{"アサショウリュウ"},
+			Pos:    "カスタム人名",
+		},
+	}
+
+	if !reflect.DeepEqual(rec, expected) {
+		t.Errorf("got %v, expected %v", rec, expected)
+	}
+}