PURPOSE: To highly precisely work an irregular-shape molded product of a complicated form by providing a working base which is slid by working reaction of a specific value or more and rotatable at the feed speed of the working ability limit of a working means, and a copying mechanism.

CONSTITUTION: A working base 2 on which a work piece 1 of an irregular-shape molded product, which base is slid by working reaction of a specific value or more and rotatable at the feed speed of the working ability limit of a working means, and a copying mechanism 3 copying along the end surface of the work piece 1 so that the working tool of the working means regularly makes contact with the end surface of the workpiece 1 in the optimum working state to continuously continue the working are provided. The workpiece in which a cylinder, a rectangle, a flat surface and a curved surface are coexistent is continuously worked. The working base 2 is formed of a first rotating base 7 provided with a rated speed driving device, and a second rotating base 9 placed on the first rotating base 7 through a bearing, and slid or idled by a fixed external force or more.