A rotary shutter adapted to be used in an electronic still camera comprises a rotatable shutter having shutter openings which are variable in size. The shutter is rotated by an electric motor in order to open and close intermittently an exposure aperture of the camera. A phase detector for detecting the phase of rotation of the shutter member provides a series of phase signal, and cooperates with a signal generator for generating stop signals in synchronism with the phase signals when a particular shutter speed is selected and a circuit for braking the motor to stop the shutter member. Responsive to the particular shutter speed selecting operation, the shutter opening is opened to its maximum size and the rotary shutter is simultaneously stopped quickly in position so as to open fully the exposure aperture of the camera.