Herein disclosed is an imaging device having an imaging optical system, the device including: an imaging element configured to include a plurality of first pixels and a plurality of second pixels arranged along a predetermined direction; a first processor configured to execute focal detection processing by a phase difference detection system based on charge signals obtained from the plurality of second pixels; and a second processor configured to execute specific processing based on charge signals obtained from the plurality of first pixels, the specific processing being different from the focal detection processing by a phase difference detection system and being necessary for a function of the imaging device.