To change the gap of a film gate in accordance with a blownie-sized film even after closing a back cover and winding the film.

A pressure plate 34 is supported on a back cover 10 so as to be freely moved between a position of coming into contact with a pressure plate receiving surface and a position of retreating toward the back cover 10. On the outer part of the back cover 10, a switching knob 33 which is selectively operated in accordance of the film type is installed. In the case of selectively operating the switching knob 33, a slide plate 41 is moved behind the pressure plate 34 and between a position where pin members 48 are pushed into opening 47 installed at four corners of the pressure plate 42 through a pressing surface 56 and a position where the pin members 48 are retreated from the openings 47 through a recessed surface 57. When the pin members 48 retreat from the openings, the pressure plate 34 comes into contact with the pressure plate receiving surface, and a tunnel gap is made narrower, on the other hand, in the case the pin members 48 are pushed into the openings 47, the pin members 48 come into contact with the pressure plate receiving surface, then, the pressure plate 34 is retreated toward the back cover 10, then, the tunnel gap is enlarged.