An electric discharge machining device that performs processing by applying a voltage pulse to space between the processing electrode and the workpiece and suitably switching the polarity of the voltage pulse attains both desired processing accuracy and desired controllability. The electric discharge machining device is provided with the first to fourth switching elements. The controlling unit that controls these switching elements, when setting a period time in which the first switching element is turned on, a period of time in which the fourth switching element is in an on-state in the same period, and, when setting a period time in which the second switching element is turned on, a period of time in which the third switching element is in an on-state in the same period so that a desired voltage pulse is applied to the space between the processing electrode and the workpiece.