Method of controlling electric discharge machine

A method of controlling an electric discharge machine having an advance control step for relatively moving and controlling in a forward direction an electrode and a workpiece to which a voltage is applied, thereby to perform electric discharge machining on the workpiece, by the use of an electric discharge caused between the electrode and the workpiece and a retraction control step of relatively moving and controlling the electrode and the workpiece in a backward direction in accordance with a retraction command, in the method of controlling the electric discharge machine, the retraction control step comprising the steps of:

• determining a state of the electric discharge machining in accordance with said retraction command;
• selecting a class corresponding to the electric discharge machining state from among a plurality of differing stored classes of retraction control information items indicating retracting control conditions different from one another and each differing class including a different retraction limit and a different retraction speed;
• and
• moving and controlling said electrode and said workpiece relatively in the backward direction on the basis of the selected class of retraction control information items.