To prevent the collection of working chips by a short-circuit current, and reduce the flow generated on the surface of a workpiece in powder electric discharge machining by stopping the application of a working pulse when a short-circuit is caused between an electrode and the workpiece.

When a working form is complicated, the circulation of a working fluid 11 in a working part is deteriorated to make the discharge of working chips difficult. When the discharge of working chips is not satisfactorily performed, powder 113 and the working chips are stayed between an electrode 102 and a workpiece 103 and apt to cause a short-circuit. When a short-circuit is caused between the electrode 102 and the workpiece 103, the output of a short-circuit detecting circuit 106 becomes 'L'. Therefore, the output of an OR circuit 110 becomes 'L', and the output of an AND circuit also becomes 'L'. Consequently, a switching element 104 is laid in OFF state to stop the application of voltage.