diff --git a/src/main/java/org/ntlab/citrusserver/repositories/AccountManager.java b/src/main/java/org/ntlab/citrusserver/repositories/AccountManager.java
index 7ed0764..bd65aae 100644
--- a/src/main/java/org/ntlab/citrusserver/repositories/AccountManager.java
+++ b/src/main/java/org/ntlab/citrusserver/repositories/AccountManager.java
@@ -2,17 +2,15 @@
 
 import org.ntlab.citrusserver.entities.Account;
 import org.springframework.stereotype.Repository;
-
-import java.lang.reflect.Array;
 import java.util.*;
 
 import java.util.HashMap;
 
 @Repository
 public class AccountManager {
-    private HashMap<String, Account> accounts = new HashMap<String, Account>(); //keyにaccountId,valueにAccount
+    private final HashMap<String, Account> accounts = new HashMap<String, Account>(); //keyにaccountId,valueにAccount
 
-    private HashMap<String, String> accountToken = new HashMap<>(); //keyがaccountId,valueがtoken
+    private final HashMap<String, String> accountToken = new HashMap<>(); //keyがaccountId,valueがtoken
 
     // アカウントの一覧をリストとして返す(GET)
     public Set<String> getAccountsID() {
@@ -33,7 +31,10 @@
 
     //accountIdとtokenを比較してtrueかfalseを返す
     public boolean checkToken(String accountId, String token) {
-        return accountToken.get(accountId).equals(token);
+        if(accounts.containsKey(accountId)) {
+            return accountToken.get(accountId).equals(token);
+        }
+        return false;
     }
 
     // 指定されたアカウントの情報を返す(GET)