A motion transforming apparatus for transforming a continuous rotary motion of an input shaft into a motion of a predetermined type of an output shaft through a motion transmitting cam device. The fluctuating torque loaded on the input shaft by the motion transmitting cam device is compensated by torque compensating cam device and pneumatic cylinder device for applying a load on the torque compensating cam device. The pneumatic cylinder device includes a cylinder and a piston, and the pressure of the gas in the cylinder compressed or expanded by the reciprocating piston acts on the torque compensating cam device, thereby applying a compensating torque on the input shaft.