Provided is an image sensor having a pixel includes a photoelectric conversion element; a capacitor which is connected between the photoelectric conversion element; a reset circuit which resets a potential of a node between the photoelectric conversion element and the capacitor; an amplifier circuit which outputs a signal corresponding to the potential of the node; and a switch which controls electrical conduction between the amplifier circuit and a vertical signal line. When the node is brought into an electrically floating state, the potential of the optical signal is stored in the node in a state of being inverted. When an optical signal is detected while the potential is stored in the node, the potential of the node increases in accordance with an output potential of the photoelectric conversion element, and thus the potential of the node corresponds to a difference in potential between the optical signals in different light-receiving periods.