Abstract: A rotary shutter of a motion picture camera comprises a pair of fan-shaped sectors which are capable of changing the angle of opening formed thereby. The sector shaft is rotated through a gear train by a claw driving shaft which in turn is rotated by a driving motor. The gear train comprises a pair of gear train means either of which is selectively used to transmit the rotation of the claw driving shaft to the sector shaft. The ratio of the rate of revolution of one shaft to that of the other is changed by changing the gear train means. A switchover means is provided to switchover the gear train from one to the other. The switchover means is associated with means for changing the angle of opening formed by the sectors. In the mode of the prolonged time exposure, the speed of revolution of the sector is reduced to the half of that of the sector in the mode of the normal motion picture.