A focus detection sensor includes a line sensor comprised of a pair of sensor arrays in which a plurality of pixels are arranged. The sensor arrays include a pixel of a first type having an arrangement for transferring charges generated by a photoelectric conversion device to a corresponding memory device and causing the memory device to integrate the charges during a charge accumulation period, and a pixel of a second type having an arrangement for integrating, in the pixel, the charges generated by the photoelectric conversion device during the charge accumulation period without transferring the charges to the memory device until the end of the charge accumulation period, and transferring the charges to the corresponding memory device when the charge accumulation period has ended. An accurate charge accumulation result can be obtained by a simple arrangement.