To provide an optical mechanism which is simple in structure, is simple in its control operation, and can accurately stop a rotating member.

A charge mechanism 10 of the optical mechanism includes: a charge lever 7 which is biased by a torsion spring 13 and charges a spring for biasing a movable mirror moving back and forth between an entering position where it enters an optical path of an imaging optical system and a retreating position where it retreats from the optical path of the imaging optical system or a mechanical shutter for adjusting exposure time of an imaging device; a cam 4 which is a member to rotate, and a member to perform charge of the spring performed in the charge lever 7 and release thereof; and a locking lever 11 which suppresses inertial rotation of the cam 4 by locking with a portion of the cam 4 or a portion of the charge lever 7 by kinetic energy produced when performing release after charging operation.