To simplify a structure of a diaphragm controller.

This diaphragm controller is constituted to turn a diaphragm driving lever 403 and a diaphragm control lever 402 by a stepping motor 411 through a worm gear composed of a first diaphragm gear 421 and a second diaphragm gear 422 and a cam mechanism composed of a diaphragm cam 423 and a cam follower 424. Consequently, since a diaphragm mechanism 400 can be reset by only driving force of the stepping motor 411 by devising a cam profile of the diaphragm cam 423, it is unnecessary for this diaphragm controller to receive auxiliary power to be supplied from a mechanism for resetting a main mirror or the like. As a result, a structure of the diaphragm mechanism 400 can be simplified because the mechanism for receiving auxiliary power to be supplied from the mechanism for resetting the main mirror or the like becomes unnecessary.