PURPOSE: To prevent any displacement of a guide support arm, while preventing splash and leakage of a machining liquid by providing a prescribed clearance between the through hole of a seal plate and the guide support arm penetrating said hole and collecting the machining liquid leaked from this clearance in a machining liquid collection tank right below the clearance.

CONSTITUTION: The device is constituted in such a way that a Y axis moving device 8 placed on a X axis moving device 4 and connected to a lower arm 3 through a lower arm supporter 9 is provided and a seal plate 15 and the lower arm is moved in X axis direction simultaneously and a prescribed clearance is set non-contactingly between the seal plate 15 and the lower arm 3 penetrating a seal plate through hole and the machining liquid leaked from this clearance may be introduced to the opening port of a machining liquid collection tank installed on a bed 2 while preventing its splash by bellows 19 whose both ends are connected to the lower arm 3 and the seal plate 15 on the outer side of a machining tank 1 and whose lower side is opened.