PURPOSE: To restrain vibration of the electrode and prevent it from being cut, by furnishing a coupler, having elasticity in the direction of twisting, between a feed roller for running the wire electrode and a drive motive and by absorbing thereby variation of the tension.

CONSTITUTION: A wire electrode 2 situated in a slit 1a provided in a work 1 moves up from below the work 1. A drive motor 15 is coupled with the shaft 12a for a feed roller 12 to drive the electrode 2 through a coupler 14, and a pinch roller 13 is pivoted rotatably at the tip of an arm 16 whose one end is pivoted at the column. In case the electrode 2 is not deposited on the work 1 but just contacting, the joint piece of the coupler deflects to absorb the unbalance of tension for drawup of the wire electrode.