A photoelectric conversion apparatus is provided. The apparatus comprises a substrate including two light receiving regions in which light receiving devices are arranged; electrode pads arranged on the substrate; and a readout circuit arranged on the substrate and configured to read out signals from the light receiving regions. The electrode pads include an output pad for outputting a signal, and a power supply pad for supplying power to the light receiving regions or the readout circuit. Each of the light receiving regions has a shape in which a first direction is taken as a longitudinal direction, the light receiving regions are arranged along a second direction with an interval therebetween, the second direction intersecting the first direction, and one or more pads of the electrode pads is sandwiched by the light receiving regions in the second direction.