diff --git a/server/domain/task/model/taskMethod.ts b/server/domain/task/model/taskMethod.ts
index f2fc211..8bc9230 100644
--- a/server/domain/task/model/taskMethod.ts
+++ b/server/domain/task/model/taskMethod.ts
@@ -1,13 +1,13 @@
 import type { TaskCreateVal, TaskEntity, TaskUpdateVal } from 'api/@types/task';
 import assert from 'assert';
-import { randomUUID } from 'crypto';
 import { deletableTaskIdParser, taskIdParser } from 'service/idParsers';
+import { ulid } from 'ulid';
 import type { TaskDeleteVal } from './taskEntity';
 
 export const taskMethod = {
   create: (val: TaskCreateVal): TaskEntity => {
     return {
-      id: taskIdParser.parse(randomUUID()),
+      id: taskIdParser.parse(ulid()),
       done: false,
       label: val.label,
       createdTime: Date.now(),
diff --git a/server/package-lock.json b/server/package-lock.json
index 4c9e1db..33eef76 100644
--- a/server/package-lock.json
+++ b/server/package-lock.json
@@ -14,6 +14,7 @@
         "dotenv": "^16.4.5",
         "fastify": "^4.26.2",
         "nodemailer": "^6.9.13",
+        "ulid": "^2.3.0",
         "velona": "^0.8.0",
         "zod": "^3.23.6"
       },
@@ -4692,6 +4693,14 @@
         "node": ">=14.17"
       }
     },
+    "node_modules/ulid": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/ulid/-/ulid-2.3.0.tgz",
+      "integrity": "sha512-keqHubrlpvT6G2wH0OEfSW4mquYRcbe/J8NMmveoQOjUqmo+hXtO+ORCpWhdbZ7k72UtY61BL7haGxW6enBnjw==",
+      "bin": {
+        "ulid": "bin/cli.js"
+      }
+    },
     "node_modules/unbox-primitive": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/unbox-primitive/-/unbox-primitive-1.0.2.tgz",
@@ -8384,6 +8393,11 @@
       "integrity": "sha512-vcI4UpRgg81oIRUFwR0WSIHKt11nJ7SAVlYNIu+QpqeyXP+gpQJy/Z4+F0aGxSE4MqwjyXvW/TzgkLAx2AGHwQ==",
       "dev": true
     },
+    "ulid": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/ulid/-/ulid-2.3.0.tgz",
+      "integrity": "sha512-keqHubrlpvT6G2wH0OEfSW4mquYRcbe/J8NMmveoQOjUqmo+hXtO+ORCpWhdbZ7k72UtY61BL7haGxW6enBnjw=="
+    },
     "unbox-primitive": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/unbox-primitive/-/unbox-primitive-1.0.2.tgz",
diff --git a/server/package.json b/server/package.json
index ca9b2ea..fd76c5a 100644
--- a/server/package.json
+++ b/server/package.json
@@ -24,6 +24,7 @@
     "dotenv": "^16.4.5",
     "fastify": "^4.26.2",
     "nodemailer": "^6.9.13",
+    "ulid": "^2.3.0",
     "velona": "^0.8.0",
     "zod": "^3.23.6"
   },
diff --git a/server/service/sendMail.ts b/server/service/sendMail.ts
index 231c029..3d386b1 100644
--- a/server/service/sendMail.ts
+++ b/server/service/sendMail.ts
@@ -1,10 +1,10 @@
 import { APP_NAME } from 'api/@constants';
 import assert from 'assert';
-import { randomUUID } from 'crypto';
 import { InbucketAPIClient } from 'inbucket-js-client';
 import { createTransport } from 'nodemailer';
 import type Mail from 'nodemailer/lib/mailer';
 import type SMTPTransport from 'nodemailer/lib/smtp-transport';
+import { ulid } from 'ulid';
 import { SMTP_HOST, SMTP_PASS, SMTP_PORT, SMTP_USER } from './envValues';
 
 const transport = createTransport({
@@ -33,7 +33,7 @@ if (import.meta.vitest) {
   const inbucketClient = new InbucketAPIClient(process.env.INBUCKET_URL);
 
   test('sendMail', async () => {
-    const from = `${randomUUID()}@localhost`;
+    const from = `${ulid()}@localhost`;
     const text = 'aaa';
 
     await sendMail({ to: { name: 'hoge', address: 'aa@example.com' }, subject: 'test', text });