In order to obtain an electric-discharge-machining power supply apparatus that can flow discharge current pulses through the machining gap uniformly and efficiently, and can realize reduction of the amount of electrode wear in machining in the alternate current pulse system, in an electric-discharge-machining power supply apparatus (2) for applying electric-discharge-machining pulse voltage to a machining gap between a machining electrode (8) and an object (9) to be machined, wherein a circuit (22) composed of a parallel connection of a rectifying element (24) and a resistive element (23) is inserted in series along a wiring path extending from an electric-discharge pulse generating unit (6) to the machining gap, and the rectifying element (23) is so connected as to cause machining pulse currents to flow in an intended direction during the electric discharge generation.