A photoelectric conversion element includes a plurality of pixels to receive light; and a signal processor to process a signal of the pixels. The signal processor includes: a first element, being a transistor, having a first effective channel width through which a current can effectively pass through in the first element; and a second element, being a transistor, having a second effective channel width through which a current can effectively pass through in the second element. The first effective channel width of the first element is larger than the second effective channel width of the second element.