To realize a stable clutch mechanism of small size and simple structure.

A principal portion of the driving force clutch mechanism is constituted of a rotation gear 1 rotated by a motor 1.0 disposed in a camera 30, a feed screw 3 capable of integrally rotating with the rotation gear 1 and of moving in a thrust direction while rotating with respect to the rotation gear 1, a compression spring 4 disposed at one end of the feed screw 3 and energizing the feed screw 3 in the thrust direction, and a feed nut 2 screwed with the feed screw 3, provided to be movable in the thrust direction interlocking with the rotation of the feed screw 3 and engaged to a pop up stroboscope mechanism 20 disposed in the camera 30.