diff --git a/Mark-In/Sources/App/AuthUserManager.swift b/Mark-In/Sources/App/AuthUserManager.swift
new file mode 100644
index 0000000..871285c
--- /dev/null
+++ b/Mark-In/Sources/App/AuthUserManager.swift
@@ -0,0 +1,46 @@
+//
+//  AuthManager.swift
+//  Mark-In
+//
+//  Created by 이정동 on 5/8/25.
+//
+
+// TODO: Core 모듈로 이전 예정
+
+import Foundation
+
+import FirebaseAuth
+
+struct AuthUser {
+  let id: String
+}
+
+protocol AuthUserManager {
+  var user: AuthUser? { get }
+  
+  func save(_ user: AuthUser)
+  func load()
+  func clear()
+}
+
+@Observable
+final class AuthUserManagerImpl: AuthUserManager {
+  var user: AuthUser?
+  
+  init() {
+    self.load()
+  }
+  
+  func load() {
+    guard let currentUser = Auth.auth().currentUser else { return }
+    self.user = AuthUser(id: currentUser.uid)
+  }
+  
+  func save(_ user: AuthUser) {
+    self.user = user
+  }
+  
+  func clear() {
+    user = nil
+  }
+}
diff --git a/Mark-In/Sources/App/DIContainer.swift b/Mark-In/Sources/App/DIContainer.swift
new file mode 100644
index 0000000..c6de151
--- /dev/null
+++ b/Mark-In/Sources/App/DIContainer.swift
@@ -0,0 +1,56 @@
+//
+//  DIContainer.swift
+//  Mark-In
+//
+//  Created by 이정동 on 5/5/25.
+//
+
+import Foundation
+
+import LinkMetadataKit
+import LinkMetadataKitInterface
+
+// TODO: 코어 모듈로 이전
+final class DIContainer {
+  static let shared = DIContainer()
+  private var dependencies: [String: Any] = [:]
+  
+  private init() {}
+  
+  func register<T>(_ dependency: T) {
+    let key = String(describing: T.self)
+    dependencies[key] = dependency
+  }
+  
+  func resolve<T>() -> T {
+    let key = String(describing: T.self)
+    let dependency = dependencies[key]
+    
+    guard let dependency = dependency as? T else {
+      fatalError("\(key)는 register되지 않았어어요. resolve 부르기전에 register 해주세요")
+    }
+    
+    return dependency
+  }
+}
+
+extension DIContainer {
+  func registerDependencies() {
+    
+    /// Core
+    let linkMetadataProvider: LinkMetadataProvider = LinkMetadataProviderImpl()
+    let authUserManager: AuthUserManager = AuthUserManagerImpl()
+    
+    register(linkMetadataProvider)
+    register(authUserManager)
+    
+    /// Repository
+    let folderRepository: FolderRepository = FolderRepositoryImpl()
+    let linkRepository: LinkRepository = LinkRepositoryImpl(
+      linkMetadataProvider: linkMetadataProvider
+    )
+    
+    register(folderRepository)
+    register(linkRepository)
+  }
+}
diff --git a/Mark-In/Sources/App/Mark_InApp.swift b/Mark-In/Sources/App/Mark_InApp.swift
index a945642..6bbcf17 100644
--- a/Mark-In/Sources/App/Mark_InApp.swift
+++ b/Mark-In/Sources/App/Mark_InApp.swift
@@ -20,11 +20,13 @@ struct Mark_InApp: App {
     
     configureFirebase()
     configureGoogleSignIn()
+    
+    DIContainer.shared.registerDependencies()
   }
   
   var body: some Scene {
     WindowGroup {
-      MainView()
+      RootView()
         .frame(minWidth: 500, minHeight: 500)
         .onOpenURL { url in
           GIDSignIn.sharedInstance.handle(url)
diff --git a/Mark-In/Sources/App/RootView.swift b/Mark-In/Sources/App/RootView.swift
new file mode 100644
index 0000000..9c758de
--- /dev/null
+++ b/Mark-In/Sources/App/RootView.swift
@@ -0,0 +1,29 @@
+//
+//  RootView.swift
+//  Mark-In
+//
+//  Created by 이정동 on 5/5/25.
+//
+
+import SwiftUI
+
+import DesignSystem
+
+struct RootView: View {
+  
+  @State private var authUserManager: AuthUserManager = DIContainer.shared.resolve()
+  
+  var body: some View {
+    ZStack {
+      if authUserManager.user != nil {
+        MainView()
+      } else {
+        LoginView()
+      }
+    }
+  }
+}
+
+#Preview {
+  RootView()
+}
diff --git a/Mark-In/Sources/Feature/Common/Reducer.swift b/Mark-In/Sources/Feature/Common/Reducer.swift
index 0df23a5..0f30140 100644
--- a/Mark-In/Sources/Feature/Common/Reducer.swift
+++ b/Mark-In/Sources/Feature/Common/Reducer.swift
@@ -7,14 +7,13 @@
 
 import Foundation
 
+@MainActor
 protocol Reducer {
   associatedtype State
   associatedtype Action
   
-  @MainActor
   func send(_ action: Action)
   
-  @MainActor
   func reduce(state: inout State, action: Action) -> Effect<Action>
 }
 
diff --git a/Mark-In/Sources/Feature/Login/LoginView.swift b/Mark-In/Sources/Feature/Login/LoginView.swift
index e413a96..5d39f4e 100644
--- a/Mark-In/Sources/Feature/Login/LoginView.swift
+++ b/Mark-In/Sources/Feature/Login/LoginView.swift
@@ -117,7 +117,7 @@ private struct SignInButtonList: View {
 }
 
 private struct SignInButton: View {
-  let provider: OAuthProvider
+  let provider: SocialSignInProvider
   
   let action: () -> Void
   
diff --git a/Mark-In/Sources/Feature/Login/LoginViewModel.swift b/Mark-In/Sources/Feature/Login/LoginViewModel.swift
index cdd764c..9a2c7d4 100644
--- a/Mark-In/Sources/Feature/Login/LoginViewModel.swift
+++ b/Mark-In/Sources/Feature/Login/LoginViewModel.swift
@@ -17,7 +17,7 @@ import Util
 @Observable
 final class LoginViewModel: Reducer {
   struct State {
-    var isSignInSuccess: Bool = false
+    // TODO: 로그인 실패 시 알림 화면을 보여줄 상태 구현 생각 중
   }
   
   enum Action {
@@ -27,12 +27,17 @@ final class LoginViewModel: Reducer {
     case signInError(SignInError)
     
     case firebaseAuthRequest(AuthCredential)
-    case firebaseAuthResponse(Result<Void, Error>)
+    case firebaseAuthResponse(Result<String, Error>)
     
     case empty
   }
   
   private(set) var state: State = .init()
+  private let authUserManager: AuthUserManager
+  
+  init() {
+    self.authUserManager = DIContainer.shared.resolve()
+  }
   
   func send(_ action: Action) {
     let effect = reduce(state: &state, action: action)
@@ -108,9 +113,9 @@ final class LoginViewModel: Reducer {
       return .run {
         do {
           /// Firebase 인증 요청
-          let _ = try await Auth.auth().signIn(with: credential)
+          let response = try await Auth.auth().signIn(with: credential)
           
-          return .firebaseAuthResponse(.success(()))
+          return .firebaseAuthResponse(.success(response.user.uid))
         } catch {
           return .firebaseAuthResponse(.failure(error))
         }
@@ -118,8 +123,9 @@ final class LoginViewModel: Reducer {
 
     case .firebaseAuthResponse(let result):
       switch result {
-      case .success(_):
-        state.isSignInSuccess = true
+      case .success(let id):
+        let user = AuthUser(id: id)
+        authUserManager.save(user)
       case .failure(let error):
         // TODO: 에러 처리 필요
         let _ = error as? AuthErrorCode
@@ -137,9 +143,9 @@ final class LoginViewModel: Reducer {
     case .none:
       break
     case .run(let action):
-      Task {
+      Task.detached { [weak self] in
         let newAction = await action()
-        await send(newAction)
+        await self?.send(newAction)
       }
     }
   }
diff --git a/Mark-In/Sources/Feature/Main/MainViewModel.swift b/Mark-In/Sources/Feature/Main/MainViewModel.swift
index 6aaed15..136f4c3 100644
--- a/Mark-In/Sources/Feature/Main/MainViewModel.swift
+++ b/Mark-In/Sources/Feature/Main/MainViewModel.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-@MainActor @Observable
+@Observable
 final class MainViewModel: Reducer {
   struct State {
     var isLoading: Bool = true
diff --git a/Shared/Util/Sources/OAuthProvider.swift b/Shared/Util/Sources/OAuthProvider.swift
index be1629f..c5cb681 100644
--- a/Shared/Util/Sources/OAuthProvider.swift
+++ b/Shared/Util/Sources/OAuthProvider.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 
-public enum OAuthProvider {
+public enum SocialSignInProvider {
   case apple
   case google
 }