PURPOSE: To have sure operations without trouble, stopping elsewhere than the regular and set positions, and certain reciprocating motions by connecting a pair of engaging means with a reciprocation means, wherein the engaging means are to engage a forward moving part and return moving part alternately.

CONSTITUTION: Each of a pair of engaging means (a, a) is composed of a chuck device 8 for an endless member 1, which is installed in the lower part of a reciprocation means 7 consisting of a traveling table whereon a material for processing, etc., is placed, and a stator 9 which pinches the member 1 together with the chuck device 8, and these means engage alternately a forward moving part (i) and a return moving part (ii) of the endless member 1. The engaging means (a) are arranged as facing the endless member 1, and the chuck means 8 is borne rotatably at the top of the stator 9 mounted to the reciprocation means 7 so as to engage the V-belt of the endless member 1, and further art air cylinder is connected with the tail of the chuck device 8.