The accuracy of a binary decision on a photon incident on a pixel is improved.An imaging device includes a generation unit and a decision unit. The generation unit generates a digital value indicating the amount of charge stored by photons incident on a pixel during an exposure period based on a signal output by the pixel. The decision unit compares a threshold value set for each pixel having similar conversion efficiency at the time of conversion of the amount of charge stored in the pixel into a digital value generated by the generation unit, with the generated digital value, and makes a decision on the entrance of a photon into the pixel that output the signal.