diff --git a/Assets/Tests/Editor/SetupWizardWindowTests.cs b/Assets/Tests/Editor/SetupWizardWindowTests.cs
index 95e31b66b..6fcc5febb 100644
--- a/Assets/Tests/Editor/SetupWizardWindowTests.cs
+++ b/Assets/Tests/Editor/SetupWizardWindowTests.cs
@@ -779,6 +779,58 @@ public void GetSkillsButtonTextForSetupWizard_ReturnsExpectedLabel(
             Assert.That(label, Is.EqualTo(expectedLabel));
         }
 
+        [Test]
+        public void ShouldShowSkillsInstalledDialog_WhenTargetsAreMissing_ReturnsTrue()
+        {
+            // Verifies that Setup Wizard keeps the success dialog for first install.
+            List<SkillSetupTargetInfo> targets = new()
+            {
+                CreateSkillTarget(
+                    hasSkillsDirectory: true,
+                    SkillInstallState.Missing)
+            };
+
+            bool shouldShowDialog = SetupWizardWindow.ShouldShowSkillsInstalledDialog(targets);
+
+            Assert.That(shouldShowDialog, Is.True);
+        }
+
+        [Test]
+        public void ShouldShowSkillsInstalledDialog_WhenAnyTargetIsOutdated_ReturnsFalse()
+        {
+            // Verifies that Setup Wizard suppresses the success dialog for skill updates.
+            List<SkillSetupTargetInfo> targets = new()
+            {
+                CreateSkillTarget(
+                    hasSkillsDirectory: true,
+                    SkillInstallState.Missing),
+                CreateSkillTarget(
+                    hasSkillsDirectory: true,
+                    SkillInstallState.Outdated)
+            };
+
+            bool shouldShowDialog = SetupWizardWindow.ShouldShowSkillsInstalledDialog(targets);
+
+            Assert.That(shouldShowDialog, Is.False);
+        }
+
+        [Test]
+        public void ShouldShowSkillsInstalledDialog_WhenAnyTargetUsesDifferentLayout_ReturnsFalse()
+        {
+            // Verifies that Setup Wizard suppresses the success dialog for skill layout updates.
+            List<SkillSetupTargetInfo> targets = new()
+            {
+                CreateSkillTarget(
+                    hasSkillsDirectory: true,
+                    SkillInstallState.Missing,
+                    hasDifferentLayoutSkills: true)
+            };
+
+            bool shouldShowDialog = SetupWizardWindow.ShouldShowSkillsInstalledDialog(targets);
+
+            Assert.That(shouldShowDialog, Is.False);
+        }
+
         [TestCase(SkillInstallState.Installed, false, true, "setup-target-item__status--installed")]
         [TestCase(SkillInstallState.Checking, false, true, "setup-target-item__status--checking")]
         [TestCase(SkillInstallState.Outdated, false, true, "setup-target-item__status--outdated")]
diff --git a/Assets/Tests/Editor/UnityCliLoopSettingsWindowCliActionTests.cs b/Assets/Tests/Editor/UnityCliLoopSettingsWindowCliActionTests.cs
index 8c8c208dc..756b2eb76 100644
--- a/Assets/Tests/Editor/UnityCliLoopSettingsWindowCliActionTests.cs
+++ b/Assets/Tests/Editor/UnityCliLoopSettingsWindowCliActionTests.cs
@@ -1,6 +1,7 @@
 using NUnit.Framework;
 using UnityEngine;
 
+using io.github.hatayama.UnityCliLoop.Domain;
 using io.github.hatayama.UnityCliLoop.Presentation;
 
 namespace io.github.hatayama.UnityCliLoop.Tests.Editor
@@ -131,6 +132,36 @@ public void IsCliUpdateNeeded_UsesDispatcherMinimumVersion(
             Assert.That(result, Is.EqualTo(expected));
         }
 
+        [TestCase(SkillInstallState.Missing, false, true)]
+        [TestCase(SkillInstallState.Outdated, false, false)]
+        [TestCase(SkillInstallState.Missing, true, false)]
+        public void ShouldShowSkillsInstalledDialog_ReturnsExpectedValue(
+            SkillInstallState installState,
+            bool hasDifferentLayoutSkills,
+            bool expected)
+        {
+            // Verifies that Settings keeps the success dialog for first install only.
+            SkillSetupTargetInfo targetInfo = CreateSkillTarget(installState, hasDifferentLayoutSkills);
+
+            bool result = UnityCliLoopSettingsWindow.ShouldShowSkillsInstalledDialog(targetInfo);
+
+            Assert.That(result, Is.EqualTo(expected));
+        }
+
+        private static SkillSetupTargetInfo CreateSkillTarget(
+            SkillInstallState installState,
+            bool hasDifferentLayoutSkills)
+        {
+            return new SkillSetupTargetInfo(
+                "Claude Code",
+                ".claude",
+                "--claude",
+                hasSkillsDirectory: true,
+                hasExistingSkills: true,
+                hasDifferentLayoutSkills,
+                installState);
+        }
+
         private static UnityCliLoopSettingsWindow.CliPrimaryButtonAction ParseAction(string action)
         {
             return (UnityCliLoopSettingsWindow.CliPrimaryButtonAction)
diff --git a/Packages/src/Editor/Presentation/Setup/SetupWizardWindow.cs b/Packages/src/Editor/Presentation/Setup/SetupWizardWindow.cs
index 9e8600c8e..e1fdffff5 100644
--- a/Packages/src/Editor/Presentation/Setup/SetupWizardWindow.cs
+++ b/Packages/src/Editor/Presentation/Setup/SetupWizardWindow.cs
@@ -779,6 +779,15 @@ internal static bool HasSkillUpdateForSetupWizard(
                         || target.HasDifferentLayoutSkills));
         }
 
+        internal static bool ShouldShowSkillsInstalledDialog(
+            IEnumerable<SkillSetupTargetInfo> targets)
+        {
+            Debug.Assert(targets != null, "targets must not be null");
+            return targets.All(target =>
+                target.InstallState != SkillInstallState.Outdated
+                && !target.HasDifferentLayoutSkills);
+        }
+
         internal static bool ShouldUseFirstInstallSkillsUi(string lastSeenSetupWizardVersion)
         {
             return string.IsNullOrEmpty(lastSeenSetupWizardVersion);
@@ -1316,6 +1325,7 @@ private async void HandleInstallSkills()
                 : FilterInstallableSkillTargets(targets);
             if (installableTargets.Count == 0) return;
 
+            bool shouldShowSkillsInstalledDialog = ShouldShowSkillsInstalledDialog(installableTargets);
             _isInstallingSkills = true;
             UpdateSkillsStep(true, targets);
 
@@ -1325,7 +1335,10 @@ await _skillSetupUseCase.InstallSkillFilesAsync(
                     installableTargets,
                     !_installSkillsFlat,
                     CancellationToken.None);
-                EditorDialogHelper.ShowSkillsInstalledDialog();
+                if (shouldShowSkillsInstalledDialog)
+                {
+                    EditorDialogHelper.ShowSkillsInstalledDialog();
+                }
             }
             finally
             {
diff --git a/Packages/src/Editor/Presentation/UnityCliLoopSettingsWindow.cs b/Packages/src/Editor/Presentation/UnityCliLoopSettingsWindow.cs
index 275130f7a..9dc105773 100644
--- a/Packages/src/Editor/Presentation/UnityCliLoopSettingsWindow.cs
+++ b/Packages/src/Editor/Presentation/UnityCliLoopSettingsWindow.cs
@@ -736,6 +736,16 @@ private SkillInstallState GetSelectedTargetInstallState(bool includeFreshnessChe
         private SkillInstallState GetSelectedTargetInstallState(
             string projectRoot,
             bool includeFreshnessCheck)
+        {
+            SkillSetupTargetInfo targetInfo = GetSelectedTargetInfo(projectRoot, includeFreshnessCheck);
+            return string.IsNullOrEmpty(targetInfo.DirName)
+                ? SkillInstallState.Missing
+                : targetInfo.InstallState;
+        }
+
+        private SkillSetupTargetInfo GetSelectedTargetInfo(
+            string projectRoot,
+            bool includeFreshnessCheck)
         {
             SkillsTargetSelection selection = SkillsTargetSelectionResolver.Resolve(
                 _skillsTarget,
@@ -746,9 +756,7 @@ private SkillInstallState GetSelectedTargetInstallState(
             SkillSetupTargetInfo targetInfo = targets
                 .FirstOrDefault(target => target.DirName == selection.DirectoryName);
 
-            return string.IsNullOrEmpty(targetInfo.DirName)
-                ? SkillInstallState.Missing
-                : targetInfo.InstallState;
+            return targetInfo;
         }
 
         private void CancelSkillInstallStateRefresh()
@@ -967,6 +975,12 @@ internal static bool IsCliUpdateNeeded(string cliVersion, bool cliIsDispatcher)
             return EvaluateCliSetupCompatibility(cliVersion, cliIsDispatcher).NeedsUpdate;
         }
 
+        internal static bool ShouldShowSkillsInstalledDialog(SkillSetupTargetInfo targetInfo)
+        {
+            return targetInfo.InstallState != SkillInstallState.Outdated
+                && !targetInfo.HasDifferentLayoutSkills;
+        }
+
         private static CliSetupCompatibilityState EvaluateCliSetupCompatibility(
             string cliVersion,
             bool cliIsDispatcher)
@@ -1019,6 +1033,10 @@ private async void HandleInstallSkills()
                 return;
             }
 
+            string projectRoot = UnityCliLoopPathResolver.GetProjectRoot();
+            SkillSetupTargetInfo selectedTargetInfo =
+                GetSelectedTargetInfo(projectRoot, includeFreshnessCheck: true);
+            bool shouldShowSkillsInstalledDialog = ShouldShowSkillsInstalledDialog(selectedTargetInfo);
             CancelSkillInstallStateRefresh();
             _isInstallingSkills = true;
             RefreshCliSetupSection();
@@ -1040,7 +1058,10 @@ await _skillSetupUseCase.InstallSkillFilesAsync(
                     new List<SkillSetupTargetInfo> { target },
                     !_installSkillsFlat,
                     CancellationToken.None);
-                EditorDialogHelper.ShowSkillsInstalledDialog();
+                if (shouldShowSkillsInstalledDialog)
+                {
+                    EditorDialogHelper.ShowSkillsInstalledDialog();
+                }
             }
             finally
             {