An optical system includes: a first optical element； a first movable frame； a holding frame； a voice coil motor； a first position detection unit configured to detect information related to a position of the first movable frame with respect to the holding frame and generate a first position signal； a determination unit configured to determine whether the first position signal is normal； and a drive control unit configured to perform, when the determination unit determines that the first position signal is normal, first drive control for driving the first movable frame by controlling, based on the first position signal, a current allowed to flow in the coil or configured to perform, when the determination unit determines that the first position signal is not normal, second drive control for driving the first movable frame by flowing a current with a predetermined value in the coil.
