To prevent increase in the consumptive power even when a pump device is used for a long time and provide a sphygmomanometer superior in the repressuring characteristic and free from noise by mounting a polarizaed permanent magnet on one end of an air chamber, assembling a permanent magnet polarized in a plurality of poles in a motor output shaft, and executing the pumping action by the attaraction and repulsion generated between the magnets.

A rotary magnet 7 polarized in a plurality of poles in the thrust direction is fixed to an output shaft 5 of a motor portion 1. A diaphragm 11, an intermediate case body 13, an air permeable cover 15 and a case cover 17 are fixed in a case body 9. The movable magnets 21a, 21b respectively polarized in one pole are fixed on the lower faces of the air chambers 19a, 19b. Each air chamber comprises an air inlet 23 and an air outlet 25, and further comprises a check-valve element 27. An air reservoir 29 and an external of a pump communicate by an intake path 31 and an exhaust cylinder 33. The repulsion and the attraction are generated between the movable magnets 21a, 21b by the rotation of the rotary magnet 7, so that the air chambers 19a, 19b are compressed and expanded, and the pumping action can be executed.