To lower noise, secure durability, and heighten transmission efficiency and operation efficiency.

A lever member 11 of a pivotal fulcrum type lever device is so constructed that a force point Q is caused to make a circular movement by rotation of a crank pin, a fulcrum R is moved vertically on a line L-L by a fulcrum regulator 26, and the lever is oscillated round the fulcrum R. Thus, the working point P makes an elliptic motion taking the lateral direction as a major axis, and the lateral motion of the elliptic motion is accurately transmitted through a working point regulator 14 to the respective pistons 8, 9, thereby alternately sucking and compressing the gas in the respective cylinders 4, 5. In the working point regulator 14 and the fulcrum regulator 26, two rollers 16, 28 rotatably supported on the working point P or the fulcrum R are always abutted only to one guide plate. The respective rollers 16, 28 do not collide with the guide plates, and at the time of reversion, slipping can be prevented so that noise and abrasion due to a collision or a slip can be reduced.