To reduce the influence of noise in the imaging device configured with the plurality of semiconductor chips.A first semiconductor chip includes a signal input transistor in which an input signal which is a signal corresponding to incident light is input to a control terminal, a reference input transistor which forms a differential pair along with the signal input transistor and in which a reference signal is input to a control terminal, a first signal line which delivers a change in a current flowing in one of the signal input transistor and the reference input transistor as a result of comparison between the input signal and the reference signal when the current is changed in accordance with a difference between the input signal and the reference signal, and a first pad which is electrically connected to the first signal line. A second semiconductor chip includes a processing circuit which processes the result of the comparison, a second signal line which is electrically connected to the processing circuit and delivers the result of the comparison to the processing circuit, and a second pad which is electrically connected to the second signal line and the first pad.