Abstract: Coriolis motion gears can be produced in a mass-production manner and in low cost as follows: A ceiling surface of a body 8 is formed into a rotary table 9 and a drive shaft 11 is projected from a center of the rotary table. A slant portion 11a is formed at its end, and a turntable 12 on which a workpiece 13 is mounted is supported rotatably to the slant portion. The turntable 12 is rotated by the tooth number difference between the Coriolis motion gear pair A.sub.1 ' and A.sub.2 ' per one turn of the drive shaft 11 to determine a working position of the workpiece. Also, the workpiece 13 is maintained on the turntable 12 so that a swivel center P.sub.1 of the Coriolis motion gear pair is identical with a swivel center when the workpiece is installed into a gear device to take a Coriolis motion. As a result, the work surface of the workpiece takes a moving locus of the Coriolis motion gears integral with the turntable 12.