An image sensor includes: a reference signal generation unit configured to generate and output a reference signal in accordance with a predetermined voltage a plurality of pixels disposed in a two-dimensional matrix form and configured to receive light from outside, and to generate and output an imaging signal in accordance with an amount of the received light a transfer unit configured to transfer the reference signal output from the reference signal generation unit and the imaging signal output from each of the plurality of pixels, during different periods and an output unit configured to separately hold the reference signal and the imaging signal transferred from the transfer unit, sequentially switch between the reference signal and the imaging signal to output the switched signal.
