An image pickup apparatus which can photograph a high-definition image and a moving image of lower resolution at high quality and an image pickup system which uses the image pickup apparatus are provided. Unit pixel groups each of which comprises plural pixels including photoelectric conversion units and transfer transistors for transferring signal charges from the photoelectric conversion units, an amplification transistor common to the plural pixels, and the like are arranged in row and column directions. With respect to the plural unit pixel groups mutually adjacent in the row direction, control lines for controlling the transfer transistors respectively corresponding to the adjacent two photoelectric conversion units are alternately connected to an odd row and an even row in the row direction.