3-axis machine for workpiece setting error compensation unit numerical controller having

A numerical controller controls a three-axis machine tool that machines a workpiece, mounted on a table, with at least three linear axes. The numerical controller includes a workpiece mounting error compensation unit that compensates a mounting error caused when the workpiece is mounted. The workpiece mounting error compensation unit performs an error compensation with respect to an instructed linear-axis position with amounting error which is set beforehand, in order to keep a position with respect to the workpiece at a tool center point position, based on the instructed linear-axis position of the three linear axes to obtain a compensated linear-axis position. The three linear axes are driven based on the obtained compensated linear-axis position.