Presence or absence of a photon is accurately detected in an image sensor with a simple configuration. A pixel circuit generates as an input voltage a signal voltage by photoelectrically converting light when the light is incident, and generates as the input voltage a predetermined reset voltage when light is not incident. A capacitor retains the predetermined reset voltage as a retained voltage. An amplification comparator amplifies a voltage difference between the input voltage and the retained voltage. A detection comparator outputs a result of determining whether or not the amplified voltage difference is higher than a predetermined value, as a detection signal indicating detected presence or absence of light incidence.