An imaging device that includes a control unit is provided. The control unit switches between a day mode and a night mode. In the day mode, image capture is performed while an infrared cut filter is placed on an optical path, and in the night mode, image capture is performed while the infrared cut filter is removed from the optical path. Immediately after shifting from the day mode to the night mode, in the night mode, as the amount of incident light decreases, the control unit increases an irradiation intensity of an infrared irradiation portion from zero while a gain is maintained at a first gain value. When the amount of the incident light further decreases after the irradiation intensity reaches a maximum, the control portion increases the gain from the first gain value.