To lightly perform a release of a latch and operation of a grip, by preventing force from being directly applied to the latch and its locking part, even if the grip is operated.

Left-right two insertion holes 6 and 6 are arranged on a front plate 5 of a door 2 having one side end pivoted on the side end of an opening part of a casing 1. A support rod 3b turning to the rear of both left and right ends in the grip 13 is respectively inserted into these respective insertion holes 6 and 6. The rear end of the support rod 3b on the opening end side of the door 2, is linked to operation mechanisms 16 and 21 of the latch for immobilizing door opening of the door 2. The rear end of the other support rod 3b is horizontally rotatably pivoted by a pivot 11 turning in the vertical direction of the reverse surface side of the front plate 5. The door 2 can be opened by releasing engagement of the latch and the locking part arranged in the casing 1 by rotatably operating the grip 13 to the front side with the pivot 11 as the center.