diff --git a/src/api/zipcode.ts b/src/api/zipcode.ts
new file mode 100644
index 0000000..959371a
--- /dev/null
+++ b/src/api/zipcode.ts
@@ -0,0 +1,67 @@
+export type GetAddressFromZipCodeResponse = {
+  success: boolean;
+  zipcode: string;
+  prefcode?: string;
+  address1?: string;
+  address2?: string;
+};
+
+type APIResponse = {
+  status: number;
+  message: string | null;
+  results:
+    | {
+        zipcode: string; //	郵便番号	7桁の郵便番号。ハイフンなし。
+        prefcode: string; //	都道府県コード	JIS X 0401 に定められた2桁の都道府県コード。
+        address1: string; //	都道府県名
+        address2: string; //	市区町村名
+        address3: string; //	町域名
+        kana1: string; //	都道府県名カナ
+        kana2: string; //	市区町村名カナ
+        kana3: string; //
+      }[]
+    | null;
+};
+
+// 郵便番号から住所を検索するAPIを呼ぶ
+export async function getAddressFromZipCode(
+  zipcode: string
+): Promise<GetAddressFromZipCodeResponse> {
+  const url = 'https://zipcloud.ibsnet.co.jp/api/search?zipcode=' + zipcode;
+
+  try {
+    const data = await callAPI(url);
+
+    if (data.status !== 200) {
+      throw Error('ステータス不正:' + data.status);
+    }
+    if (data.results === null || data.results.length === 0) {
+      throw Error('結果0件:' + data.status);
+    }
+
+    const target = data.results[0];
+
+    // 正常返却
+    return {
+      success: true,
+      zipcode,
+      prefcode: target.prefcode,
+      address1: target.address2,
+      address2: target.address3,
+    };
+  } catch (e) {
+    if (e instanceof Error) {
+      console.error('zipcode error', e.message);
+    }
+    // エラー返却
+    return {
+      success: false,
+      zipcode,
+    };
+  }
+}
+
+async function callAPI(url: string): Promise<APIResponse> {
+  const data = await (await fetch(url)).json();
+  return data;
+}
diff --git a/src/pages/app/hooks/useInputMailStep.tsx b/src/pages/app/hooks/useInputMailStep.tsx
index 7bca1a3..d481a23 100644
--- a/src/pages/app/hooks/useInputMailStep.tsx
+++ b/src/pages/app/hooks/useInputMailStep.tsx
@@ -1,9 +1,11 @@
 import { yupResolver } from "@hookform/resolvers/yup";
 import { Box, Button, Divider, Stack, Typography } from "@mui/material";
 import { HasChildren } from "@types";
+import { getAddressFromZipCode } from "api/zipcode";
 import { FormProvider, RHFTextField } from "components/hook-form";
 import RHFDatePicker from "components/hook-form/RHFDatePicker";
 import RHFPrefCodeSelect from "components/hook-form/ex/RHFPrefCodeSelect";
+import useBackDrop from "hooks/useBackDrop";
 import useNavigateCustom from "hooks/useNavigateCustom";
 import { useForm } from "react-hook-form";
 import * as Yup from "yup";
@@ -34,6 +36,8 @@ type Props = {
   onPrev?: VoidFunction;
 };
 export default function useInputMailStep({ onNext, onPrev }: Props) {
+  const { setShowBackDrop } = useBackDrop();
+
   const form = useForm<FormProps>({
     defaultValues: {
       mail_pref_code: "",
@@ -65,6 +69,24 @@ export default function useInputMailStep({ onNext, onPrev }: Props) {
     ),
   });
 
+  const zipCode = form.watch("mail_zip_code");
+  const handleBlurZipCode = () => {
+    if (/^[0-9]{7}$/.test(zipCode)) {
+      setShowBackDrop(true);
+      getAddressFromZipCode(zipCode)
+        .then((res) => {
+          if (res.success) {
+            form.setValue("mail_pref_code", res.prefcode ?? "");
+            form.setValue("mail_address1", res.address1 ?? "");
+            form.setValue("mail_address2", res.address2 ?? "");
+          }
+        })
+        .finally(() => {
+          setShowBackDrop(false);
+        });
+    }
+  };
+
   const handleSubmit = () => {
     if (onNext) {
       onNext();
@@ -80,16 +102,17 @@ export default function useInputMailStep({ onNext, onPrev }: Props) {
   const element = (
     <FormProvider methods={form} onSubmit={form.handleSubmit(handleSubmit)}>
       <Stack spacing={2} sx={{ p: 1, m: 1 }} textAlign="left">
-        <AreaBox title="都道府県">
-          <RHFPrefCodeSelect name="mail_pref_code" size="small" />
-        </AreaBox>
         <AreaBox title="郵便番号">
           <Typography variant="body2">ハイフン無の7桁</Typography>
           <RHFTextField
             name="mail_zip_code"
             InputProps={{ startAdornment: <div>〒</div> }}
+            onBlur={handleBlurZipCode}
           />
         </AreaBox>
+        <AreaBox title="都道府県">
+          <RHFPrefCodeSelect name="mail_pref_code" size="small" />
+        </AreaBox>
         <AreaBox title="市区町村">
           <RHFTextField name="mail_address1" />
         </AreaBox>