To prevent the accuracy of position of an operating member from affecting the function of an exposure switching means.

When an operating member 15 turns from a second operative position shown by selected Figure (A) to a third operative position shown by selected Figure (B), a switching plate 61 presses and turns a switching ring 56. The switching ring 56 turns a diaphragm switching plate 43 and a shutter speed switching plate 46 to switch a diaphragm and shutter speed. When the operating member 15 is at the second operative position, since the cooperation between the switching plate 61 and the switching ring 56 is released, even if the member 15 turns slightly by fingering, the diaphragm or shutter speed does not switch carelessly. Since the diaphragm switching plate 43 starts turning near the end of turning of the switching ring 56 and its switching operation is short, even if the operating member 15 stops moving on the way, the diaphragm is maintained in the state of small or large diaphragm.