PURPOSE: To prevent the windings of a wire on a wind-up feel from collapsing, by converting the rotation of a rotary motor into the reciprocating rectilinear motion of a support member for supporting a guide member by use of a motion converting mechanism, and by controlling the rectilinear motion to a constant speed.

CONSTITUTION: The rotation of a pulse motor 42 on rotation is converted into rectilinear reciprocating motion in the direction parallel to the axial direction of a wind-up reel 8 on a shaft 49 by means of first and second links 45, 47. Accordingly, a guide roller 7 for guiding a wire electrode 10 attached to the forward end of the shaft 49 to the wind-up reel 8 is rectilinearly reciprocated. Further, the angular velocity of the pulse motor 42 which is controlled in its rotational speed by a controller 50 is changed over successively to a suitable speed for every predetermined angle so that the above-mentioned guide roller 7 is rectilinearly reciprocated at a constant speed. Thus, the wire electrode to be wound up on the wind-up reel 8 is uniformly wound up, thereby it is possible to prevent the windings of the wire electrode from collapsing.