PURPOSE: To permit the airtightness of a sealed part to be maintained by inserting the standing-up part of a pressure receiving thin film body into an annular groove and setting the sealed part crossing at right angles with the pump weight application direction and caulking said sealed part.

CONSTITUTION: In a sealed part 4B, a sealed state is formed by inserting the standing-up part 6A on the outer peripheral edge of a pressure receiving thin film body 6 into an annular groove 4D having an inverted U-shaped section and pressing and caulking said sealed part 4B. Since the caulking direction of the sealed part 4B crosses at right angles to the weight applying direction of a pump, the air tightness of the sealed part 4B is not deteriorated, even if a loading surface 4A is deformed a little by the impact generated by the weight of the pump during transport.