<p>An electric discharge machine in which electric power for working is supplied between an electrode and workpiece by an electric power unit so as to generate electric discharge between the electrode and workpiece and conduct machining on the workpiece, the electric discharge machine having a voltage detector for detecting output voltage V of a DC electric power source of the electric power unit; a current detector for detecting output current I of the DC electric power source of the electric power unit; a calculator for calculating product V.I of V and I; and a controller for controlling output electric power of the electric power unit to be constant on the basis of a difference between a working command signal for giving a predetermined electric power command and V.I. Even when load impedance fluctuates, it is possible to suppress the fluctuation of electric discharge power, so that surface roughness on a machined face of the workpiece can be made uniform.</p>
