PURPOSE: To eliminate fluid leakage and strain concentration of a diaphragm and improve durability by passing a transmission shaft for connecting a driving source and a rotor or an oscillator between both of them, and providing a diaphragm with a wave-formed section.

CONSTITUTION: A transmission shaft 10 which transmits a rotation of a rotating plate 12 of a driving motor 11 to a rotating shaft 8 is seal-penetrates a diaphragm 20, interposed between an upper casing 2 and a lower casing 3 and screening the inside space of both casings 2, 3, and the sectional shape of the diaphragm 20 is made a waveform. It is thus possible to provide complete sealing, uniformalize the deformation of the diaphragm 20 due to the movement of the transmission shaft 10, facilitating assembling and improving durability.