Photoelectric conversion apparatus and photoelectric conversion system

A photoelectric conversion apparatus comprising a first substrate and a second substrate, wherein

• the first substrate includes a plurality of first unit circuits, and each first unit circuit includes at least one photoelectric conversion element,
• the second substrate includes a plurality of second unit circuits configured to process signals output from the first substrate,
• the first substrate is stacked on the second substrate,
• the first substrate includes a first region where first unit circuits of a first group out of the plurality of first unit circuits are arranged, and a second region where first unit circuits of a second group out of the plurality of first unit circuits are arranged,
• the second substrate includes a third region where second unit circuits of a third group out of the plurality of second unit circuits are arranged, and a fourth region where second unit circuits of a fourth group out of the plurality of second unit circuits are arranged,
• the third region and the fourth region are arranged to be shifted from the first region and the second region, respectively, so that the third region and the fourth region are separated from each other, and
• a distance between the third region and the fourth region is smaller than an array pitch of the plurality of first unit circuits in the first substrate.