The invention provides a focal plane shutter for cameras. A blade room for a back blade group is formed between a shutter base plate and a middle plate and a blade room for a front blade group is formed between the middle plate and an auxiliary base plate, by separating a space between the shutter base plate and the auxiliary base plate by the middle plate. A push pin which is planted on the shutter base plate pushes a portion on the lower area of the middle plate toward the auxiliary base plate so that the middle plate bends in the shape of an arc. Also, the area of the middle plate below the exposure aperture has the narrowest width in the portion which is pushed by the push pin and the pushed portion of the middle plate has a shape by which the area of the middle plate below the exposure aperture is easy to bend. As a result, when exposure operation is performed, when the part of the slit-forming blade of the back blade group moves downwards to an exposure aperture, even though a slit-forming blade bends, the slit-forming blade is prevented from touching the edge of an opening portion of an object optical path of the middle plate.