An image reading apparatus including an image reading chip for reading an image, wherein the image reading chip includes: a terminal; a pixel portion that outputs a pixel signal and includes a light-receiving element that receives and photoelectrically converts light from the image; an output circuit that can output a signal based on the pixel signal with one of a plurality of drive capabilities including a first drive capability and a second drive capability that is larger than the first drive capability; and an output selection circuit that, based on a signal input to the terminal, selects the drive capability of the output circuit.