PURPOSE: To enable the pressurizing of an upper arm accurately upto a value of maximum blood pressure without pressurization of the upper arm excessively above or insufficiently below a necessary level by arranging an upper arm pressurization stopping means which stops a pump to direct the start of measuring a blood pressure when the vanishing of pulse wave is detected by monitoring the pulse wave.

CONSTITUTION: A photosensor emission part 11 and a photosensor photodetecting section 17 are mounted so as to pinch any one finger 19 on the side of an upper arm 21 wound with an arm band 13 between the photosensor emission part 11 and the photosensor photodetecting part 17. This hemodynamometer is so arranged to monitor a pulse wave of a signal indicating a quantity of transmission light from the photosensor photodetecting part 17 and stops the pressurization of the upper arm with a pump 7 when blood current to the finger 19 is gone with the closure of an artery under the pressurization of the upper arm. So, the driving of the pump 7 can be stopped by detecting the timing of stopping the optimum pressurization of the upper arm accurately. This eliminates excessive burden imposed on a user by pressing the upper arm at a pressurization value above the necessary level or pressing it over a long time for repressurization because of insufficient pressurization, thereby enabling the pressurization of the upper arm accurately even beyond the maximum blood pressure.