To reduce weight by enhancing torsional rigidity of a telescopic mechanism for advancing-retreating a vacuum pad 20 by an air cylinder 12.

A frame body of a box structure is constituted by fixing three plate members 4 between a base member 2 installed on the operation end of a robot and the other end side installing member 6. The air cylinder 12 is rockingly suspended and supported by an under surface of the base member 2. A support plate 18 attached with the vacuum pad 20 is connected to the tip of a piston rod 14 of this air cylinder 12. A guiding guide 8 is fixed at equal intervals to an outside surface of the installing member 6. While, three guide rods 10 are fixed to the support plate 18, and are fitted to the guiding guide 8. Since three sets of guiding guides 8 and guide rods 10 are arranged at equal intervals, that is, in an equilateral triangle shape, the torsional rigidity is enhanced, and the rigidity uniform in all directions is obtained.