diff --git a/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java b/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java
index 261e17e..5c84a49 100644
--- a/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java
+++ b/app/src/main/java/org/ntlab/acanthus_client/Acanthus.java
@@ -106,6 +106,7 @@
         SharedPreferences preferences = getSharedPreferences("prefData", MODE_PRIVATE);
         SharedPreferences.Editor editor = preferences.edit();
         editor.putInt("uid", preferenceUid);
+        this.preferenceUid = preferenceUid;
         editor.commit();
     }
 
@@ -113,6 +114,7 @@
         SharedPreferences preferences = getSharedPreferences("prefData", MODE_PRIVATE);
         SharedPreferences.Editor editor = preferences.edit();
         editor.putString("name", preferenceName);
+        this.preferenceName = preferenceName;
         editor.commit();
     }
 
@@ -120,6 +122,7 @@
         SharedPreferences preferences = getSharedPreferences("prefData", MODE_PRIVATE);
         SharedPreferences.Editor editor = preferences.edit();
         editor.putString("email", preferenceEmail);
+        this.preferenceEmail = preferenceEmail;
         editor.commit();
     }
 
@@ -127,6 +130,7 @@
         SharedPreferences preferences = getSharedPreferences("prefData", MODE_PRIVATE);
         SharedPreferences.Editor editor = preferences.edit();
         editor.putString("password", preferencePassword);
+        this.preferencePassword = preferencePassword;
         editor.commit();
     }
 
@@ -134,6 +138,7 @@
         SharedPreferences preferences = getSharedPreferences("prefData", MODE_PRIVATE);
         SharedPreferences.Editor editor = preferences.edit();
         editor.putString("token", preferenceToken);
+        this.preferenceToken = preferenceToken;
         editor.commit();
     }
 
diff --git a/app/src/main/java/org/ntlab/acanthus_client/views/login/LoginScreenActivity.java b/app/src/main/java/org/ntlab/acanthus_client/views/login/LoginScreenActivity.java
index 250f5b3..d8cc201 100644
--- a/app/src/main/java/org/ntlab/acanthus_client/views/login/LoginScreenActivity.java
+++ b/app/src/main/java/org/ntlab/acanthus_client/views/login/LoginScreenActivity.java
@@ -7,6 +7,7 @@
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.View;
+import android.widget.TextView;
 
 import org.ntlab.acanthus_client.Acanthus;
 import org.ntlab.acanthus_client.R;
@@ -44,6 +45,19 @@
         setTheme(R.style.AppTheme_NoTitleBar);//タイトルバーを消す
         init();
     }
+    //-----------------------------------------------------------------
+    @Override
+    protected void onResume() {
+        super.onResume();
+        if (hasAccount()) {
+            Acanthus acanthus = (Acanthus) getApplication();
+            TextView email = findViewById(R.id.editTextTextLoginEmail);
+            TextView password = findViewById(R.id.editTextTextLoginPassword);
+
+            email.setText(acanthus.getPreferenceEmail());
+            password.setText(acanthus.getPreferencePassword());
+        }else setDummyForm();
+    }
 
     //-----------------------------------------------------------------
     //-----------------------------------------------------------------
@@ -78,6 +92,24 @@
         startActivity(intent);
         finish();
     }
-    //-----------------------------------------------------------------
 
+    //-----------------------------------------------------------------
+    // 既にアカウントを持っている場合
+    private boolean hasAccount() {
+        Acanthus acanthus = (Acanthus) getApplication();
+        if (acanthus.getPreferenceEmail().equals("")) return false;
+        return !acanthus.getPreferencePassword().equals("");
+    }
+
+    //-----------------------------------------------------------------
+    //
+    private void setDummyForm(){
+        Acanthus acanthus = (Acanthus) getApplication();
+        TextView email = findViewById(R.id.editTextTextLoginEmail);
+        TextView password = findViewById(R.id.editTextTextLoginPassword);
+
+        email.setText("d0@dummy.com");
+        password.setText("nittalab");
+    }
+    //-----------------------------------------------------------------
 }
\ No newline at end of file
diff --git a/app/src/main/java/org/ntlab/acanthus_client/views/sign_up/SignUpActivity.java b/app/src/main/java/org/ntlab/acanthus_client/views/sign_up/SignUpActivity.java
index cbef89d..ed1facc 100644
--- a/app/src/main/java/org/ntlab/acanthus_client/views/sign_up/SignUpActivity.java
+++ b/app/src/main/java/org/ntlab/acanthus_client/views/sign_up/SignUpActivity.java
@@ -50,17 +50,22 @@
         Acanthus acanthus = (Acanthus) getApplication();
 
         // 各フォーム取得
-        String name = binding.editTextTextSignUpPersonName.getText().toString();
-        String emailAddress = binding.editTextTextSignUpEmailAddress.getText().toString();
-        String password = binding.editTextTextSignUpPassword.getText().toString();
+        TextView nameForm = findViewById(R.id.editTextTextSignUpPersonName);
+        TextView emailForm = findViewById(R.id.editTextTextSignUpEmailAddress);
+        TextView passwordForm = findViewById(R.id.editTextTextSignUpPassword);
 
-        Call<AccountUidJson> call = accountsRest.createAccount(name, emailAddress, password);
+        String name = nameForm.getText().toString();
+        String email = emailForm.getText().toString();
+        String password = passwordForm.getText().toString();
+
+        Call<AccountUidJson> call = accountsRest.createAccount(name, email, password);
         call.enqueue(new Callback<AccountUidJson>() {
             @Override
             public void onResponse(Call<AccountUidJson> call, Response<AccountUidJson> response) {
                 if (response.isSuccessful()) {
+                    acanthus.setPreferenceUid(response.body().getUid());
                     acanthus.setPreferenceName(name);
-                    acanthus.setPreferenceEmail(emailAddress);
+                    acanthus.setPreferenceEmail(email);
                     acanthus.setPreferencePassword(password);
                     transitionLoginActivity();
                 } else clearForm();