An imaging device includes pixels each including a holding portion, and an output unit, and a control unit that controls readout of pixel signals. The pixels include first to fourth pixels that output signals based on light of first to fourth wavelength ranges. A first unit pixel includes the first and second pixels but no third pixel, which share the holding portion. A second unit pixel includes the first and third pixels but no second pixel, which share the holding portion. A third unit pixel includes the first and fourth pixels but neither second nor third pixel, which share the holding portion. The control unit reads, from the first unit pixel, a signal in which signals of the first and second pixels are added in the holding portion, and reads, from the third unit pixel, a signal in which signals of the first pixels are added in the holding portion.