Photoelectric conversion apparatus and optical detection system

An apparatus comprising:

• a layer having a light incident surface and including an avalanche photodiode;
• and
• a wiring structure disposed on a surface of the layer on an opposite side to the light incident surface,
• wherein the avalanche photodiode includes a first region of a first conductivity type in which charges having same polarity as signal carriers are majority carriers and a second region of a second conductivity type,
• a first voltage is supplied to the second region through a region of the second conductivity type,
• the wiring structure includes a first wiring arranged to supply the first voltage to the region of the second conductivity type and positioned closest to the layer, and a second wiring disposed in a same wiring layer as the first wiring is disposed and arranged to supply a second voltage to the first region,
• the first wiring has an opening,
• the second wiring is disposed in the opening of the first wiring in plan view, and
• the opening of the first wiring has five or more sides in plan view.