PURPOSE: To obtain remarkably improved accuracy and speed by increasing the relative transfer speed of electrodes for a work, when the work comes to the corner part processing in the condition when the electrodes are relatively inclined against the work.

CONSTITUTION: When the work is processed with inclination at its center at the wire-cut discharge processor for four axis control taper cut, the relative speed between the wire electrodes 5 and the work 1 is zero, and the relative speed increases as the processing comes close to the top surface of the work 1. Accordingly, in that case top side guide roller 3 moves at the speed higher than that. In this invention, in order to perform processing at higher accuracy, the processing width per unit time is kept at a constant value by changing the speed of relative inclination which the electrode 5 makes against the work 1 and the unit surface of processing at every part of the work is made at constant value.