A photoelectric conversion apparatus includes a photoelectric conversion unit with a semiconductor region of a first conduction type, an amplifying transistor, and a contact. The contact supplies, via a semiconductor region of a second conduction type arranged along a side surface and a bottom surface of an element isolation region, a reference voltage to the semiconductor region of the second conduction-type arranged below source and drain regions of the amplifying transistor in a region below a gate electrode of the amplifying transistor.