A photoelectric conversion device includes a pixel including a transfer transistor transferring signal charges generated in a photoelectric conversion portion from a charge accumulation region to a floating diffusion region, and a peripheral transistor forming a peripheral circuit for controlling a read-out operation of a pixel signal based on the signal charges from the pixel. A gate electrode of the transfer transistor and the floating diffusion region are separated from each other by a first distance in a plan view. A gate electrode and a drain region of the peripheral transistor are separated from each other by a second distance smaller than the first distance in a plan view.