PURPOSE: To stabilize the opening and closing operation of a sector and improve the accuracy of the exposure time, by starting the sector closing operation by releasing the tying of the closing ring a prescribed time after the start of the opening operation of the sector and, simultaneously, stopping the opening ring by braking.

CONSTITUTION: An iron piece lever 40 is supported by a supporting shaft 39 so that it can cooperate with a suction type electromagnet 38 arranged on a shutter substrate 1 and a brake lever 42 is supported by a supporting shaft 41. An electromagnet 21 is actuated so as to actuate a closing ring 3 to obtain a desired exposure time after an opening ring 2 is actuated and, at the same time, the electromagnet 38 is magnetized and the iron piece lever 40 is attracted by the electromagnet 40, and then, the brake lever 42 is rotated counterclockwise through a spring 45 and the revolving lever 2 is stopped by braking. Therefore, a spector 4 is closed only by the closing operation of the closing ring 3 and a stabilized accuracy improvement of the shutter speed can be realized.