diff --git a/gpu-vulkan-middle.cabal b/gpu-vulkan-middle.cabal
--- a/gpu-vulkan-middle.cabal
+++ b/gpu-vulkan-middle.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           gpu-vulkan-middle
-version:        0.1.0.73
+version:        0.1.0.74
 synopsis:       Medium wrapper for Vulkan API
 description:    Please see the README on GitHub at <https://github.com/YoshikuniJujo/gpu-vulkan-middle#readme>
 category:       GPU
@@ -67,6 +67,7 @@
       Gpu.Vulkan.Device.Enum
       Gpu.Vulkan.Device.Middle
       Gpu.Vulkan.Device.Middle.Internal
+      Gpu.Vulkan.Device.GroupDevice.Middle
       Gpu.Vulkan.Enum
       Gpu.Vulkan.Exception.Enum
       Gpu.Vulkan.Exception.Middle
@@ -149,6 +150,7 @@
       Gpu.Vulkan.DescriptorSet.Middle.Internal
       Gpu.Vulkan.DescriptorSetLayout.BindingFlags.Middle.Internal
       Gpu.Vulkan.DescriptorSetLayout.Middle.Internal
+      Gpu.Vulkan.Device.GroupDevice.Middle.Internal
       Gpu.Vulkan.Device.Middle.Types
       Gpu.Vulkan.Exception.Middle.Internal
       Gpu.Vulkan.Framebuffer.Middle.Internal
diff --git a/src/Gpu/Vulkan/Device/GroupDevice/Middle.hs b/src/Gpu/Vulkan/Device/GroupDevice/Middle.hs
new file mode 100644
--- /dev/null
+++ b/src/Gpu/Vulkan/Device/GroupDevice/Middle.hs
@@ -0,0 +1,5 @@
+{-# OPTIONS_GHC -Wall -fno-warn-tabs #-}
+
+module Gpu.Vulkan.Device.GroupDevice.Middle (CreateInfo(..)) where
+
+import Gpu.Vulkan.Device.GroupDevice.Middle.Internal
diff --git a/src/Gpu/Vulkan/Device/GroupDevice/Middle/Internal.hs b/src/Gpu/Vulkan/Device/GroupDevice/Middle/Internal.hs
new file mode 100644
--- /dev/null
+++ b/src/Gpu/Vulkan/Device/GroupDevice/Middle/Internal.hs
@@ -0,0 +1,48 @@
+{-# LANGUAGE ImportQualifiedPost #-}
+{-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE FlexibleContexts, UndecidableInstances #-}
+{-# LANGUAGE ViewPatterns #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# OPTIONS_GHC -Wall -fno-warn-tabs #-}
+
+module Gpu.Vulkan.Device.GroupDevice.Middle.Internal where
+
+import Foreign.Ptr
+import Foreign.Marshal.Alloc
+import Foreign.Marshal.Array
+import Foreign.Storable
+import Foreign.Storable.PeekPoke
+import Control.Arrow
+import Data.TypeLevel.Maybe qualified as TMaybe
+
+import Gpu.Vulkan.PhysicalDevice.Middle.Internal qualified as PhysicalDevice
+import Gpu.Vulkan.Device.GroupDevice.Core qualified as C
+
+data CreateInfo mn = CreateInfo {
+	createInfoNext :: TMaybe.M mn,
+	createInfoPhysicalDevices :: [PhysicalDevice.P] }
+
+deriving instance Show (TMaybe.M mn) => Show (CreateInfo mn)
+
+instance WithPoked (TMaybe.M mn) => WithPoked (CreateInfo mn) where
+	withPoked' ci f = alloca \pci -> do
+		createInfoToCore ci $ \cci -> poke pci cci
+		f . ptrS $ castPtr pci
+
+createInfoToCore :: WithPoked (TMaybe.M mn) =>
+	CreateInfo mn -> (C.CreateInfo -> IO a) -> IO ()
+createInfoToCore CreateInfo {
+	createInfoNext = mnxt,
+	createInfoPhysicalDevices = (id &&& length) -> (pds, pdc)
+	} f =
+	putStrLn "createInfoToCore begin" >>
+	withPoked' mnxt \pnxt -> withPtrS pnxt \(castPtr -> pnxt') ->
+	allocaArray pdc \ppds -> do
+		pokeArray ppds (phdToCore <$> pds)
+		() <$ f C.CreateInfo {
+			C.createInfoSType = (),
+			C.createInfoPNext = pnxt',
+			C.createInfoPhysicalDeviceCount = fromIntegral pdc,
+			C.createInfoPPhysicalDevices = ppds }
+	where
+	phdToCore (PhysicalDevice.P p) = p
diff --git a/src/Gpu/Vulkan/PhysicalDevice/Middle/Internal.hsc b/src/Gpu/Vulkan/PhysicalDevice/Middle/Internal.hsc
--- a/src/Gpu/Vulkan/PhysicalDevice/Middle/Internal.hsc
+++ b/src/Gpu/Vulkan/PhysicalDevice/Middle/Internal.hsc
@@ -5,7 +5,7 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE FlexibleContexts, UndecidableInstances #-}
 {-# LANGUAGE ViewPatterns #-}
-{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE StandaloneDeriving, GeneralizedNewtypeDeriving #-}
 {-# OPTIONS_GHC -Wall -fno-warn-tabs #-}
 
 module Gpu.Vulkan.PhysicalDevice.Middle.Internal (
@@ -69,7 +69,7 @@
 
 #include <vulkan/vulkan.h>
 
-newtype P = P C.P deriving Show
+newtype P = P C.P deriving (Show, Storable)
 
 enumerate :: Instance.M.I -> IO [P]
 enumerate (Instance.M.I ist) = map P <$> alloca \pdvcc ->