An optical system for a CMOS sensor includes an aspherical lens with which an exit pupil distance appears short in a central region of an imaging plane and long in a peripheral region of the imaging plane. The aspherical lens functions such that the exit pupil distance monotonously increases from a central region of the imaging plane toward a peripheral region of the imaging plane. In addition, pupil correction is performed in accordance with an exit pupil distance d which satisfies (d1+d2)/2