To provide a method for discriminating front and rear faces of a cup-shaped workpiece by a simple means without using electronic equipment such as a sensor, and a disc type parts feeder having simple setup changing work and adjusting work for enabling the method for discriminating the front and rear faces.

This parts feeder is provided with a doughnut-shaped rotary disc installed to horizontally rotate, a disc installed to rotate by being inclined to the inside of the rotary disc, and a driving mechanism to rotate the rotary disc and the disc. The rotary disc is a saw blade type rotary disc having a saw blade at the doughnut-shaped inside. A pressing plate is installed on an upper side of the saw blade type rotary disc. The cup-shaped workpiece mounted on the saw blade type rotary disc is pressed to the inside by the pressing plate, and the front and rear faces of the workpiece can be discriminated since the workpiece falls from the saw blade type rotary disc in a state that the workpiece turns to the back by placing an opening part down.