PURPOSE: To make the cutting surface of a circularly formed product uniform throughout its circumference by an arrangement wherein the burr of the formed product is formed into a hollow conically shaped membrane slanted from the inner end of the formed product toward its axial center and a blade is moved in the direction of diameter between the circular product and the burr.

CONSTITUTION: In forming a circular formed product 1 of rubber-like elastic substance, a burr 2 composed of a substantially hollow and conically shaped membrane 8 slanted from the internal surface end of one end of the circular formed product 1 and a substantially columnar body 4 protruded from the axial center of the membrane is caused to form. The circular formed product 1 having the burr 2 to be removed is installed to a holder 5 which is then rotated at a speed necessary for cutting. The tip of blade 7 is positioned on the extension line of the cut portion of the circular formed product 1, and then the blade 7 is caused to advance to cut the burr by the rotation of the holder 5. In this method, the initial posture of the blade is maintained until the burr is completely removed and the cutting surface is uniformly cut throughout its entire circumference.