PURPOSE: To make the supporting condition of a work stable for enhancing cutting accuracy, by supporting the work in the vicinity of a cutter.

CONSTITUTION: A plurality of rod-like blades 3 each having a guide surface 5 at its front end are radially arranged around a rod-like work W in the front of a rotary cutter 1. The blades 3 are positioned at positions where the guide surfaces 5 abut against the work W, by means of a positioning mechanism including an arm 13, a cam follower 20, etc., and are urged in the direction in which the guide surfaces 5 are made into contact under pressure with the work W, by means of an urging mechanism including a piston 46, etc. With this arrangement, the work W may be supported in the vicinity of a cutter 1.