diff --git a/src/ain.ts b/src/ain.ts
index aadf681..8b6c3fc 100644
--- a/src/ain.ts
+++ b/src/ain.ts
@@ -50,12 +50,22 @@ export default class AinModule {
     return this.ain!.signer
   }
 
-  getAddress() {
+  async getAddress() {
     this.checkAinInitiated();
     try {
       return this.getSigner().getAddress(); 
     } catch (e) {
-      return null;
+      throw new Error("Need to set up an account or signer first.");
+    }
+  }
+
+  isAccountSetUp() {
+    try {
+      this.checkAinInitiated();
+      this.getSigner().getAddress();
+      return true;
+    } catch (e) {
+      return false;
     }
   }
 
@@ -73,8 +83,9 @@ export default class AinModule {
   }
 
   async getBalance() {
-    const address = this.getAddress();
-    return address ? await this.ain!.wallet.getBalance(address) : null;
+    const address = await this.getAddress();
+    const balancePath = `/accounts/${address}/balance`;
+    return await this.ain!.db.ref(balancePath).getValue();
   }
 
   async getValue(path: string) {
@@ -110,6 +121,13 @@ export default class AinModule {
   private handleTxResultWrapper(operation: Function) {
     return async (args: any) => {
       const res = await operation(args);
+      // ainWalletSigner return txHash or undefined.
+      if (typeof res === 'string') {
+        return res;
+      } else if (res === undefined) {
+        throw new Error(`Failed to build transaction.`);
+      }
+      // defaultSigner return a result object of transactions.
       const { tx_hash, result } = res;
       if (this.hasFailedOpResultList(result)) {
         throw new Error(
diff --git a/src/ainize.ts b/src/ainize.ts
index 4d113d7..3d9f9f8 100644
--- a/src/ainize.ts
+++ b/src/ainize.ts
@@ -40,7 +40,7 @@ export default class Ainize {
   async login(privateKey: string) {
     this.ain.setDefaultAccount(privateKey);
     await this.handler.connect();
-    console.log('login success! address:', this.ain.getAddress());
+    console.log('login success! address:', await this.ain.getAddress());
   }
 
   /**
@@ -49,7 +49,7 @@ export default class Ainize {
   async loginWithSigner() {
     const signer = new AinWalletSigner;
     this.ain.setSigner(signer);
-    console.log('login success! address: ', this.ain.getAddress());
+    console.log('login success! address: ', await this.ain.getAddress());
   }
 
   /**
@@ -61,24 +61,11 @@ export default class Ainize {
     console.log('logout success!');
   }
 
-  /**
-   * Throw error if user doesn't log in.
-   * @returns {}
-   */
-  async checkLoggedIn() {
-    const address = await this.ain.getAddress();
-    if (!address) {
-      throw new Error('You should login first.');
-    }
-  }
-
   async getAddress(): Promise<string> {
-    await this.checkLoggedIn();
-    return await this.ain.getAddress()!;
+    return await this.ain.getAddress();
   }
 
   async getAinBalance(): Promise<number> {
-    await this.checkLoggedIn();
     return await this.ain.getBalance() || 0;
   }
 
@@ -90,10 +77,9 @@ export default class Ainize {
    */
   // TODO(yoojin, woojae): Deploy container, advanced.
   async deploy({serviceName, billingConfig, serviceUrl}: deployConfig): Promise<Service> {
-    await this.checkLoggedIn();
     // TODO(yoojin, woojae): Add container deploy logic.
     const result = await new Promise(async (resolve, reject) => {
-      const deployer = this.ain.getAddress()!;
+      const deployer = await this.ain.getAddress();
       if (!billingConfig) {
         billingConfig = {
           ...DEFAULT_BILLING_CONFIG,
diff --git a/src/controllers/appController.ts b/src/controllers/appController.ts
index 21899f6..09b1114 100644
--- a/src/controllers/appController.ts
+++ b/src/controllers/appController.ts
@@ -124,7 +124,7 @@ export default class AppController {
   }
 
     async checkCostAndBalance(appName: string, value: string) {
-      const requesterAddress = this.ain.getAddress();
+      const requesterAddress = await this.ain.getAddress();
       const billingConfig = (await this.getBillingConfig(appName));
       const token = value.split(' ').length;
       let cost = token * billingConfig.costPerToken;
diff --git a/src/controllers/serviceController.ts b/src/controllers/serviceController.ts
index 7f65b6d..cd7ff83 100644
--- a/src/controllers/serviceController.ts
+++ b/src/controllers/serviceController.ts
@@ -50,7 +50,7 @@ export default class ServiceController {
   async chargeCredit(serviceName: string, amount: number): Promise<string> {
     this.checkRunning(serviceName);
     const transferKey = Date.now();
-    const userAddress = this.ain.getAddress(); 
+    const userAddress = await this.ain.getAddress(); 
     const depositAddress = await this.getDepositAddress(serviceName);
     const op_list: SetOperation[] = [
       getTransferOp(userAddress, depositAddress, transferKey.toString(), amount),
@@ -66,13 +66,14 @@ export default class ServiceController {
   }
 
   async getCreditBalance(serviceName: string): Promise<number> {
-    const userAddress = this.ain.getAddress();
+    const userAddress = await this.ain.getAddress();
+    console.log("userAddress in getCreditBalance", userAddress)
     const balancePath = Path.app(serviceName).balanceOfUser(userAddress);
     return await this.ain.getValue(balancePath) as number | 0;
   }
 
   async getCreditHistory(serviceName: string): Promise<creditHistories> {
-    const userAddress = this.ain.getAddress();
+    const userAddress = await this.ain.getAddress();
     const creditHistoryPath = Path.app(serviceName).historyOfUser(userAddress);
     return await this.ain.getValue(creditHistoryPath) as creditHistories;
   }
@@ -82,7 +83,7 @@ export default class ServiceController {
     const result = await new Promise(async (resolve, reject) => {
       requestKey = requestKey || Date.now().toString();
       try {
-        const requesterAddress = this.ain.getAddress();
+        const requesterAddress = await this.ain.getAddress();
         const responsePath = Path.app(serviceName).response(requesterAddress, requestKey.toString());
         await this.handler.subscribe(responsePath, resolve);
         const requestPath = Path.app(serviceName).request(requesterAddress, requestKey);
@@ -121,9 +122,7 @@ export default class ServiceController {
   }
 
   checkLoggedIn(): void {
-    try {
-      !this.ain.getAddress();
-    } catch(error) {
+    if (!this.ain.isAccountSetUp()) {
       throw new Error('You should login first.');
     }
   }
@@ -132,8 +131,8 @@ export default class ServiceController {
     this.checkLoggedIn();
     const adminPath = `/manage_app/${serviceName}/config/admin`;
     const adminList = await this.ain.getValue(adminPath);
-    if(!adminList[this.ain.getAddress()]) {
-      throw new Error('You are not admin');
+    if(!adminList[(await this.ain.getAddress())]) {
+      throw new Error('You are not a service admin.');
     }
   }
 }
\ No newline at end of file
diff --git a/src/handlers/handler.ts b/src/handlers/handler.ts
index d82c7c5..230bdf5 100644
--- a/src/handlers/handler.ts
+++ b/src/handlers/handler.ts
@@ -32,7 +32,7 @@ export default class Handler {
   }
 
   private async disconnectedCb() {
-    if(AinModule.getInstance().isDefaultAccountExist()) {
+    if(await AinModule.getInstance().getAddress()) {
       console.log('disconnected. reconnecting...');
       await this.connect();
     }
@@ -49,7 +49,7 @@ export default class Handler {
       },
       (valueChangedEvent: any) => {
         this.unsubscribe(subscribeId);
-        resolve(valueChangedEvent.values.after.data);
+        resolve(valueChangedEvent.values.after);
       },
       (err) => {
         throw new Error(err.message);