An imaging device is provided. The device comprises: an imaging unit in which a plurality of pixels each including a photoelectric conversion element are arranged; a signal processor configured to process a signal output from the imaging unit; and a storage device configured to store the signal output from the imaging unit and transfer the signal to the signal processor. The storage device stores a plurality of image signals output by the plurality of pixels arranged in the imaging unit as a plurality of sub-frames and then outputs a sub-frame satisfying a predetermined condition out of the plurality of sub-frames as a signal for configuring a single frame.