A new form relief grinding method for an involute pinion cutter with almost no regrinding error is proposed. In the method, the tooth flanks of pinion cutter are finished as those of involute helical gears with excessive (larger and smaller) helix angles than that of the pinion cutter. The obtained results are as follows: (1) In the conventional generating method, it is impossible to finish an involute pinion cutter with no profile error. (2) The profiles of grinding wheel to finish a pinion cutter under excessive helical motions are calculated. (3) Profile errors of a pinion cutter being finished by the proposed method are smaller than those finished by the conventional method. (4) The finishing test of pinion cutter (mn = 2.5 mm, N = 39, β = 15°) was conducted on the NC form grinding machine and the pinion cutter with the accurate cutting edges was obtained. © 2000, The Japan Society of Mechanical Engineers. All rights reserved.