diff --git a/packages/maker/src/App.tsx b/packages/maker/src/App.tsx
index f54d387..61fe8f8 100644
--- a/packages/maker/src/App.tsx
+++ b/packages/maker/src/App.tsx
@@ -8,6 +8,7 @@ import SplitPane from 'react-split-pane';
 import './common/SplitPane.scss';
 import { connect, MapStateToProps } from 'react-redux';
 import { StoreType } from './State';
+import NotificationView from './notification/NotificationView';
 
 interface StateProps {
     isOpened: boolean
@@ -39,20 +40,23 @@ class App extends React.Component<StateProps> {
 
     public render() {
         return (
-            <div className={styles.app}>
-                <div className={styles.mainToolbar}>
-                    <MainToolbar></MainToolbar>
+            <>
+                <NotificationView />
+                <div className={styles.app}>
+                    <div className={styles.mainToolbar}>
+                        <MainToolbar></MainToolbar>
+                    </div>
+                    <div className={styles.editArea}>
+                        <SplitPane split="horizontal" defaultSize={300} primary="second">
+                            <MapEdit></MapEdit>
+                            <PartsSelect></PartsSelect>
+                        </SplitPane>
+                    </div>
+                    <div className={this.getInfoPanelClassName()}>
+                        <InfoPanel></InfoPanel>
+                    </div>
                 </div>
-                <div className={styles.editArea}>
-                    <SplitPane split="horizontal" defaultSize={300} primary="second">
-                        <MapEdit></MapEdit>
-                        <PartsSelect></PartsSelect>
-                    </SplitPane>
-                </div>
-                <div className={this.getInfoPanelClassName()}>
-                    <InfoPanel></InfoPanel>
-                </div>
-            </div>
+            </>
         );
     }
 }
diff --git a/packages/maker/src/State.ts b/packages/maker/src/State.ts
index b36dc9b..b21d57e 100644
--- a/packages/maker/src/State.ts
+++ b/packages/maker/src/State.ts
@@ -2,6 +2,7 @@ import { LoadState, LoadReducer, INITIAL_STATE as LOAD_INITIAL_STATE } from "./l
 import { PartsState, INITIAL_STATE as PARTS_INITIAL_STATE, ObjectPartsReducer, MapPartsReducer } from "./parts/PartsState";
 import { MapState, INITIAL_STATE as MAP_INITIAL_STATE, MapReducer } from "./map/MapStates";
 import { InfoPanelState, INITIAL_STATE as INFOPANEL_INITIAL_STATE, InfoPanelReducer } from "./info/InfoPanelState";
+import { NotificationState, INITIAL_STATE as NOTIFICATION_INITIAL_STATE, NotificationReducer } from "./notification/NotificationStates";
 import { WWAData } from "@wwawing/common-interface";
 import { WWADataReducer } from "./wwadata/WWADataState";
 import { createStore, applyMiddleware } from "redux";
@@ -21,7 +22,8 @@ export interface StoreType {
     objParts: PartsState,
     mapParts: PartsState,
     imageUrl: string|null,
-    info: InfoPanelState
+    info: InfoPanelState,
+    notification: NotificationState
 }
 
 /**
@@ -35,7 +37,8 @@ const INITIAL_STATE: StoreType = {
     objParts: PARTS_INITIAL_STATE,
     mapParts: PARTS_INITIAL_STATE,
     imageUrl: null,
-    info: INFOPANEL_INITIAL_STATE
+    info: INFOPANEL_INITIAL_STATE,
+    notification: NOTIFICATION_INITIAL_STATE
 }
 
 const actionCreator = actionCreatorFactory();
@@ -86,7 +89,8 @@ const reducer = reducerWithInitialState(INITIAL_STATE)
         map: MapReducer(state.map, action),
         objParts: ObjectPartsReducer(state.objParts, action),
         mapParts: MapPartsReducer(state.mapParts, action),
-        info: InfoPanelReducer(state.info, action)
+        info: InfoPanelReducer(state.info, action),
+        modal: NotificationReducer(state.notification, action)
     }))
 
 export const Store = createStore(
diff --git a/packages/maker/src/common/MapView/MapCanvas.tsx b/packages/maker/src/common/MapView/MapCanvas.tsx
index 2546760..468b479 100644
--- a/packages/maker/src/common/MapView/MapCanvas.tsx
+++ b/packages/maker/src/common/MapView/MapCanvas.tsx
@@ -111,8 +111,12 @@ const MapCanvas: React.FC<Props> = props => {
      * 指定した座標から各パーツ種類のパーツ番号を取得します
      * @param chipX 
      * @param chipY 
+     * @returns その座標にあるパーツ番号 (範囲外の場合は 0)
      */
     const getPartsNumberOnTarget = (chipX: number, chipY: number, type: PartsType) => {
+        if (chipX < 0 || chipX >= mapWidth || chipY < 0 || chipY >= mapWidth) {
+            return 0;
+        }
         switch (type) {
             case PartsType.MAP:
                 return map[chipY][chipX];
diff --git a/packages/maker/src/info/InfoPanelState.ts b/packages/maker/src/info/InfoPanelState.ts
index b0c2dfe..0a08037 100644
--- a/packages/maker/src/info/InfoPanelState.ts
+++ b/packages/maker/src/info/InfoPanelState.ts
@@ -1,6 +1,7 @@
 import actionCreatorFactory from "typescript-fsa";
 import { reducerWithInitialState } from "typescript-fsa-reducers";
 import { PartsType } from "../classes/WWAData";
+import { showError } from "../notification/types/ErrorNotification";
 
 /**
  * InfoPanel のモードです。
@@ -49,14 +50,13 @@ export const InfoPanelReducer = reducerWithInitialState(INITIAL_STATE)
         viewMode: payload.mode
     }))
     .case(showPartsEdit, (state, payload) => {
-        // TODO: Reducer の中にアラートを表示するのはちょっと良くないかもしれない。別の場所に移しておきたい。
         if (payload.number === 0) {
             switch (payload.type) {
                 case PartsType.OBJECT:
-                    alert("パーツ番号０の物体は編集できません。\nこのパーツはマップの物体を消去するときに指定してください。");
+                    showError("パーツ番号０の物体は編集できません。\nこのパーツはマップの物体を消去するときに指定してください。");
                     break;
                 case PartsType.MAP:
-                    alert("パーツ番号０の背景は編集できません。\nこのパーツはマップの背景を消去するときに指定してください。");
+                    showError("パーツ番号０の背景は編集できません。\nこのパーツはマップの背景を消去するときに指定してください。");
             }
             return state;
         }
diff --git a/packages/maker/src/notification/NotificationItem.ts b/packages/maker/src/notification/NotificationItem.ts
new file mode 100644
index 0000000..91496c2
--- /dev/null
+++ b/packages/maker/src/notification/NotificationItem.ts
@@ -0,0 +1,15 @@
+import React from "react";
+import { ErrorNotificationState } from "./types/ErrorNotification";
+
+/**
+ * 通知で表示するアイテムです。
+ */
+export type NotificationItem = ErrorNotificationState;
+
+/**
+ * types ディレクトリ以降の各通知の内容表示コンポーネントを定義づける型情報です。
+ * @todo 各通知固有のパラメーターをもたせる場合、どうしたら良いか考える
+ */
+export type NotificationItemView = React.FC<{
+
+}>;
diff --git a/packages/maker/src/notification/NotificationStates.ts b/packages/maker/src/notification/NotificationStates.ts
new file mode 100644
index 0000000..13835d7
--- /dev/null
+++ b/packages/maker/src/notification/NotificationStates.ts
@@ -0,0 +1,26 @@
+import { NotificationItem } from "./NotificationItem";
+import actionCreatorFactory from "typescript-fsa";
+import { reducerWithInitialState } from "typescript-fsa-reducers";
+
+export type NotificationState = {
+    items: NotificationItem[]
+};
+
+export const INITIAL_STATE: NotificationState = {
+    items: []
+};
+
+const actionCreator = actionCreatorFactory();
+/**
+ * 通知を発生させます。
+ */
+export const notify = actionCreator<{ content: NotificationItem }>("SHOW_ERROR");
+
+export const NotificationReducer = reducerWithInitialState<NotificationState>(INITIAL_STATE)
+    .case(notify, (state, params) => {
+        const newState = Object.assign({}, state);
+        newState.items = state.items.slice();
+        newState.items.push(params.content);
+
+        return newState;
+    })
diff --git a/packages/maker/src/notification/NotificationView.module.scss b/packages/maker/src/notification/NotificationView.module.scss
new file mode 100644
index 0000000..4ab97d6
--- /dev/null
+++ b/packages/maker/src/notification/NotificationView.module.scss
@@ -0,0 +1,5 @@
+.notificationView {
+    display: absolute;
+    right: 0;
+    bottom: 0;
+}
diff --git a/packages/maker/src/notification/NotificationView.tsx b/packages/maker/src/notification/NotificationView.tsx
new file mode 100644
index 0000000..09c3860
--- /dev/null
+++ b/packages/maker/src/notification/NotificationView.tsx
@@ -0,0 +1,28 @@
+import React from "react";
+
+import { NotificationItem } from "./NotificationItem";
+import styles from "./NotificationView.module.scss";
+import { useSelector } from "react-redux";
+import { NotificationItemView } from "./NotificationItem";
+import { ErrorNotification } from "./types/ErrorNotification";
+
+const NotificationView: React.FC<{}> = () => {
+    const notificationItems = useSelector(state => state.notification.items);
+
+    return (
+        <div className={styles.notificationView}>
+            {notificationItems.map(notificationItem => {
+                const NotificationItemComponent = NotificationItemViewTable[notificationItem.type];
+                return (
+                    <NotificationItemComponent />
+                )
+            })}
+        </div>
+    );
+};
+
+const NotificationItemViewTable: { [type in NotificationItem["type"] ]: NotificationItemView } = {
+    "ERROR": ErrorNotification
+}
+
+export default NotificationView;
diff --git a/packages/maker/src/notification/types/ErrorNotification.tsx b/packages/maker/src/notification/types/ErrorNotification.tsx
new file mode 100644
index 0000000..6e6745c
--- /dev/null
+++ b/packages/maker/src/notification/types/ErrorNotification.tsx
@@ -0,0 +1,31 @@
+import React from "react";
+import { Message } from "semantic-ui-react";
+import { notify } from "../NotificationStates";
+import { NotificationItemView } from "../NotificationItem";
+
+export type ErrorNotificationState = {
+    type: "ERROR",
+    message: string
+};
+
+/**
+ * エラーを発生させます。
+ * @param message エラーメッセージ
+ */
+export const showError = (message: string) => {
+    notify({
+        content: {
+            type: "ERROR",
+            message
+        }
+    });
+};
+
+export const ErrorNotification: NotificationItemView = () => {
+    return (
+        <Message negative>
+            <Message.Header>エラー！</Message.Header>
+            {/*<p>{message}</p>*/}
+        </Message>
+    );
+};