In an apparatus, operation is switchable between first and second modes. In the first mode, a photoelectric conversion part and a charge storage part are released from a reset state for all pixels included in an image acquisition area to start a period, and, when a predetermined time has elapsed, the photoelectric conversion part and an overflow drain region of each pixel are turned onto end the period, and finally the charge stored in the charge storage part is transferred to the amplifier part. In the second mode, after a mechanical shutter is opened to start a period, the mechanical shutter is closed to end the period, and stored charge is transferred to the amplifier part.