PURPOSE: To provide a booster pump of a hemadynamometer of an attachment type and a large capacity, which can be measured simply and in a short time.

CONSTITUTION: This booster pump of a hemadynamometer is composed of a flexible bellows 1, a suction valve 3 made of a synthetic rubber attached to the bellows 1, and an exhaust valve made of a synthetic rubber. The suction valve 3 and the exhaust valve 4 have flow passages to allow to move a fluid only from flow-in sides 3a and 4a to flow-out sides 3b and 4b respectively, the flow-out side 3b of the suction valve 3 and the flow-in side 4a of the exhaust valve 4 are faced to a space in the bellows 1, and the air in the bellows 1 is exhausted from the exhaust valve 4 by compressing the bellows 1. The outer air is sucked into the bellows 1 from the suction valve 3 in the process of expanding and restoring the bellows 1.