In a first blade unit-driving unit which is rotated by elastic force of a first blade unit-driving spring in shooting, its driving pin rotates a first brake member counterclockwise and a second brake member clockwise against the elastic force of a coil spring fitted to a fitting shaft and against friction resistance force of a friction-providing part including a plate spring or the like at the final stage of the rotation of the first blade unit-driving unit, the plate spring being fitted to the fitting shaft, so that the first blade unit-driving unit is braked, and, at this point, one end part of the first blade unit-driving spring contacts a part to be pushed of the first brake member and controls the counterclockwise rotation of the first brake member, so that braking force to the first blade unit-driving unit acts on the first blade unit-driving unit larger and more surely.