PURPOSE: To efficiently collect a wire electrode into a collecting case, by providing a feed amount detector of the wire electrode and reciprocating the wire collecting case in the horizontal direction corresponding to a wire feed amount by a signal from said detector.

CONSTITUTION: A wire collecting motor 16 is driven by an output signal obtained from a wire feed amount detector which detects a feed amount of wire. And a wire collecting case 12, which is moved to the right direction (a) till a right end position detecting limit switch operates, is stopped in a position of a case 12b. Reversely rotating the motor 16 thereafter, the case 12 is moved in the left direction (b), and if a left end position detecting limit switch operates, the case 12 is stopped in a position of a case 12a. Hereinafter, further the motor 16 is normally rotated, and the case 12 is moved in the right direction (a). And the case 12, which performs a reciprocating motion till the case is fully filled with a wire electrode, enables electric discharge machining to be continuously performed for a long time.