A CPU 41 reads a next block (S1), and then determines whether the read block is a TCP (tool center point) control finish command “G49” or not (S2). If it is determined to be the TCP control finish command “G49”, the TCP control is finished. If it is determined not to be the TCP control finish command “G49”, whether the read block is a coordinate-system transformation command “P1” or not is determined (S3). Next, if it is determined not to be the coordinate-system transformation command “P1”, the TCP control is performed, without transforming the coordinate system, in accordance with a command of the block (S11). Next, the process returns to S1, and then the process after S1 is executed. If it is determined to be the coordinate-system transformation command “P1”, a start point (xs, ys, zs, bs, cs) and an end point (xe, ye, ze, be, ce) in a non-machine coordinate system, of the block are transformed into a start point (Xs, Ys, Zs, Bs, Cs) and an end point (Xe, Ye, Ze, Be, Ce) in a machine coordinate system, respectively (S4).