A photoelectric conversion device includes a pixel array having aperture pixels arranged so as to form rows and columns, signal lines arranged in the pixel array so as to allow readout of signals from the aperture pixels, current sources connected to the signal lines, a first voltage supply line configured to supply a first reference voltage to the aperture pixels, a first pad connected to the first voltage supply line, a bias circuit configured to supply a bias voltage to the current sources, a second voltage supply line electrically separated from the first voltage supply line, and configured to supply a second reference voltage to the bias circuit, and a second pad connected to the second voltage supply line.