PURPOSE: To profile only the necessary part concerning the parallel face to Z axis by performing a pick feed at the time when a profile locus varies by the specific movement amount in the direction of a certain angle to the specific plane under executing profiling and performing profiling in the reverse direction to the profiling direction once again.

CONSTITUTION: A stylus is moved at the specific speed in the orthogonal direc tion with a profile line 3 from a point P3 on X - Y plane and also moved verti cally along the shape of a model 1 in Z axial direction, the right and left sides of the profile line 3 are profiled by a profile width W1 respectively, a pick feed is executed by a width W2 and the surface reciprocating profile is performed. But prior to reaching the profile width W1 the stylus is moved by hz in the Z axial direction from the point P4 crossed with the profile line 3, then this movement amount is detected, the pick feed of the width W2 is performed in parallel to the profile line 3 from the point P4 and again profiling is continued in the reverse direction. Profiling is thus executed up to a point P5 with the specific locus 4 as well as the profile width W1.