To shorten a period of time for measuring the air leakage of an exhaust valve for a hemadynamometer and to improve the measurement precision therefor.

At the side of the one end of an air tube 8 having the exhaust valve 2 for the hemadynamometer mounted to the other end, an electromagnetic valve 5 for supplying air is provided. Between the electromagnetic valve 5 and the exhaust valve 2, an air tank 7 with a pressure sensor 9 is provided, and tube internal pressure P being a sensor detected value is displayed on a monitor 11 through an A/D converter 10 etc. In the vicinity of the other end of the air tube 8, an electromagnetic valve 15 for holding tube internal pressure is provided. Each time of finishing measurement, the electromagnetic valve 15 is closed, and the next measurement is carried out while the tube internal pressure P is sealed and held as it is.