A photoelectric conversion device according to one or more embodiments includes a plurality of photoelectric conversion units. A readout portion is configured to output current signals to an output line. Each of the current signals is based on an amount of charges generated by a corresponding one of the photoelectric conversion units. The readout portion includes a plurality of transistors including at least a plurality of first input transistors and a plurality of second input transistors. Each of the first input transistors and a corresponding one of the second input transistor form a differential pair. Of the plurality of the transistors, any transistors repeatedly arranged correspondingly to every one or more of the photoelectric conversion units have the same conductivity type.