A laminator 100 in which the diaphragm can be mounted simply and easily without the use of a mounting frame. The laminator 100 includes an upper chamber 110, on the bottom surface of which is mounted the diaphragm 140, and a lower chamber 120 on which the upper chamber 110 is stacked and in which is disposed a support base 130 on which a workpiece A that is to be laminated is set. The diaphragm 140 is larger than the upper chamber 110, and an excess portion of the diaphragm that protrudes outside the upper chamber when the diaphragm is mounted on the upper chamber is folded upward and clamped against the sides of the upper chamber by multiple clamps to fix the diaphragm in place on the upper chamber.