diff --git a/memoapp/.gitignore b/memoapp/.gitignore
index 359f1bc..3e50d64 100644
--- a/memoapp/.gitignore
+++ b/memoapp/.gitignore
@@ -1 +1 @@
-public/memos.json
+memos.json
diff --git a/memoapp/app.rb b/memoapp/app.rb
index 4f59076..150b337 100644
--- a/memoapp/app.rb
+++ b/memoapp/app.rb
@@ -3,8 +3,9 @@
 require 'sinatra'
 require 'sinatra/reloader'
 require 'json'
+require 'securerandom'
 
-FILE_PATH = 'public/memos.json'
+FILE_PATH = 'memos.json' # publicフォルダから移動
 
 def load_memos
   File.exist?(FILE_PATH) ? JSON.parse(File.read(FILE_PATH)) : {}
@@ -12,7 +13,7 @@ end
 
 def save_memos(memos)
   File.open(FILE_PATH, 'w') do |file|
-    file.write(JSON.pretty_generate(memos))
+    file.write(JSON.generate(memos))
   end
 end
 
@@ -31,8 +32,8 @@ end
 
 post '/memos' do
   memos = load_memos
-  id = (memos.keys.map(&:to_i).max || 0) + 1
-  memos[id.to_s] = { 'title' => params[:title], 'content' => params[:content] }
+  id = SecureRandom.uuid
+  memos[id] = { 'title' => params[:title], 'content' => params[:content] }
   save_memos(memos)
   redirect '/memos'
 end
diff --git a/memoapp/public/memos.json b/memoapp/public/memos.json
deleted file mode 100644
index d12994c..0000000
--- a/memoapp/public/memos.json
+++ /dev/null
@@ -1,10 +0,0 @@
-{
-  "1": {
-    "title": "",
-    "content": ""
-  },
-  "2": {
-    "title": "a",
-    "content": "aaa"
-  }
-}
\ No newline at end of file