diff --git a/src/Home.tsx b/src/Home.tsx
index 7017d9d..2148a47 100644
--- a/src/Home.tsx
+++ b/src/Home.tsx
@@ -1,6 +1,6 @@
 import * as React from "react";
 import { FunctionComponent, useEffect, useState } from "react";
-import BoardView from "./components/BoardView";
+import BoardView from "./components/board/BoardView";
 import { context } from "./context";
 import { RTMTWS } from "./rtmt/rtmt_websocket";
 import {
diff --git a/src/components/BoardView.tsx b/src/components/board/BoardView.tsx
similarity index 53%
rename from src/components/BoardView.tsx
rename to src/components/board/BoardView.tsx
index 61fb7e2..1d482f2 100644
--- a/src/components/BoardView.tsx
+++ b/src/components/board/BoardView.tsx
@@ -1,110 +1,11 @@
 import { Bank, MancalaGame, Pit } from "mancala.js";
 import * as React from "react";
 import { FunctionComponent, useState } from "react";
-import { Context } from "../context";
-import { getColorByBrightness } from "../util/ColorUtil";
-import BoardViewModel from "../viewmodel/BoardViewModel";
-import PitViewModel from "../viewmodel/PitViewModel";
-
-const StoneView: FunctionComponent<{ color: string }> = ({ color }) => {
-  return (
-    <div
-      style={{
-        background: color,
-        margin: "1px",
-        width: "1vw",
-        height: "1vw",
-        borderRadius: "10vw",
-        transition: "background-color 0.5s",
-      }}
-    ></div>
-  );
-};
-
-function range(size: number) {
-  var ans = [];
-  for (let i = 0; i < size; i++) {
-    ans.push(i);
-  }
-  return ans;
-}
-
-const PitView: FunctionComponent<{
-  pitViewModel: PitViewModel;
-  onClick: () => void;
-}> = ({ pitViewModel, onClick }) => {
-  const stones = [...range(pitViewModel.stoneCount)].map((i, index) => (
-    <StoneView key={index} color={pitViewModel.stoneColor} />
-  ));
-
-  return (
-    <div
-      onClick={onClick}
-      style={{
-        background: pitViewModel.pitColor,
-        margin: "5px",
-        padding: "5px",
-        borderRadius: "10vw",
-        transition: "background-color 0.5s",
-        display: "flex",
-        alignItems: "center",
-        alignContent: "center",
-        justifyContent: "center",
-        justifyItems: "center",
-        flexWrap: "wrap",
-      }}
-    >
-      {stones}
-    </div>
-  );
-};
-
-const StoreView: FunctionComponent<{
-  context: Context;
-  pitViewModel: PitViewModel;
-  gridColumn: string;
-  gridRow: string;
-}> = ({ context, pitViewModel, gridColumn, gridRow }) => {
-  const stones = [...range(pitViewModel.stoneCount)].map((i, index) => (
-    <StoneView key={index} color={pitViewModel.stoneColor} />
-  ));
-  const textColor = getColorByBrightness(
-    pitViewModel.pitColor,
-    context.themeManager.theme.textColor,
-    context.themeManager.theme.textLightColor
-  );
-  return (
-    <div
-      style={{
-        gridColumn: gridColumn,
-        gridRow: gridRow,
-        background: pitViewModel.pitColor,
-        margin: "5px",
-        borderRadius: "10vw",
-        display: "flex",
-        alignItems: "center",
-        justifyContent: "center",
-        alignContent: "center",
-        flexWrap: "wrap",
-        position: "relative",
-      }}
-    >
-      {stones}
-      <span
-        style={{
-          position: "absolute",
-          bottom: "2vw",
-          fontFamily: "monospace",
-          fontWeight: "bold",
-          fontSize: "2vw",
-          color: textColor,
-        }}
-      >
-        {stones.length}
-      </span>
-    </div>
-  );
-};
+import { Context } from "../../context";
+import BoardViewModel from "../../viewmodel/BoardViewModel";
+import PitViewModel from "../../viewmodel/PitViewModel";
+import PitView from "./PitView";
+import StoreView from "./StoreView";
 
 const BoardView: FunctionComponent<{
   game?: MancalaGame;
@@ -165,7 +66,7 @@ const BoardView: FunctionComponent<{
         background: theme.boardColor,
       }}
     >
-      {userKey === game.player2Id ? (
+      {userKey === game?.player2Id ? (
         <>
           <StoreView
             context={context}
@@ -179,7 +80,7 @@ const BoardView: FunctionComponent<{
             gridColumn="8 / 9"
             gridRow="1 / 3"
           />
-          {player1Pits.reverse()}
+          {player1Pits?.reverse()}
           {player2Pits}
         </>
       ) : (
@@ -196,7 +97,7 @@ const BoardView: FunctionComponent<{
             gridColumn="1 / 2"
             gridRow="1 / 3"
           />
-          {player2Pits.reverse()}
+          {player2Pits?.reverse()}
           {player1Pits}
         </>
       )}
diff --git a/src/components/board/PitView.tsx b/src/components/board/PitView.tsx
new file mode 100644
index 0000000..5691042
--- /dev/null
+++ b/src/components/board/PitView.tsx
@@ -0,0 +1,38 @@
+import * as React from "react";
+import { FunctionComponent } from "react";
+import Util from "../../util/Util";
+import PitViewModel from "../../viewmodel/PitViewModel";
+import StoneView from "./StoneView";
+
+
+const PitView: FunctionComponent<{
+    pitViewModel: PitViewModel;
+    onClick: () => void;
+}> = ({ pitViewModel, onClick }) => {
+    const stones = [...Util.range(pitViewModel.stoneCount)].map((i, index) => (
+        <StoneView key={index} color={pitViewModel.stoneColor} />
+    ));
+
+    return (
+        <div
+            onClick={onClick}
+            style={{
+                background: pitViewModel.pitColor,
+                margin: "5px",
+                padding: "5px",
+                borderRadius: "10vw",
+                transition: "background-color 0.5s",
+                display: "flex",
+                alignItems: "center",
+                alignContent: "center",
+                justifyContent: "center",
+                justifyItems: "center",
+                flexWrap: "wrap",
+            }}
+        >
+            {stones}
+        </div>
+    );
+};
+
+export default PitView;
\ No newline at end of file
diff --git a/src/components/board/StoneView.tsx b/src/components/board/StoneView.tsx
new file mode 100644
index 0000000..2b5e16a
--- /dev/null
+++ b/src/components/board/StoneView.tsx
@@ -0,0 +1,19 @@
+import * as React from "react";
+import { FunctionComponent } from "react";
+
+const StoneView: FunctionComponent<{ color: string }> = ({ color }) => {
+    return (
+      <div
+        style={{
+          background: color,
+          margin: "1px",
+          width: "1vw",
+          height: "1vw",
+          borderRadius: "10vw",
+          transition: "background-color 0.5s",
+        }}
+      ></div>
+    );
+  };
+
+  export default StoneView;
\ No newline at end of file
diff --git a/src/components/board/StoreView.tsx b/src/components/board/StoreView.tsx
new file mode 100644
index 0000000..375481f
--- /dev/null
+++ b/src/components/board/StoreView.tsx
@@ -0,0 +1,56 @@
+import * as React from "react";
+import { FunctionComponent } from "react";
+import { Context } from "../../context";
+import { getColorByBrightness } from "../../util/ColorUtil";
+import Util from "../../util/Util";
+import PitViewModel from "../../viewmodel/PitViewModel";
+import StoneView from "./StoneView";
+
+const StoreView: FunctionComponent<{
+    context: Context;
+    pitViewModel: PitViewModel;
+    gridColumn: string;
+    gridRow: string;
+  }> = ({ context, pitViewModel, gridColumn, gridRow }) => {
+    const stones = [...Util.range(pitViewModel.stoneCount)].map((i, index) => (
+      <StoneView key={index} color={pitViewModel.stoneColor} />
+    ));
+    const textColor = getColorByBrightness(
+      pitViewModel.pitColor,
+      context.themeManager.theme.textColor,
+      context.themeManager.theme.textLightColor
+    );
+    return (
+      <div
+        style={{
+          gridColumn: gridColumn,
+          gridRow: gridRow,
+          background: pitViewModel.pitColor,
+          margin: "5px",
+          borderRadius: "10vw",
+          display: "flex",
+          alignItems: "center",
+          justifyContent: "center",
+          alignContent: "center",
+          flexWrap: "wrap",
+          position: "relative",
+        }}
+      >
+        {stones}
+        <span
+          style={{
+            position: "absolute",
+            bottom: "2vw",
+            fontFamily: "monospace",
+            fontWeight: "bold",
+            fontSize: "2vw",
+            color: textColor,
+          }}
+        >
+          {stones.length}
+        </span>
+      </div>
+    );
+  };
+
+  export default StoreView;
\ No newline at end of file
diff --git a/src/util/Util.ts b/src/util/Util.ts
new file mode 100644
index 0000000..905b84d
--- /dev/null
+++ b/src/util/Util.ts
@@ -0,0 +1,10 @@
+
+export default class Util {
+    public static range(size: number) {
+        var ans = [];
+        for (let i = 0; i < size; i++) {
+            ans.push(i);
+        }
+        return ans;
+    }
+}