To provide a device capable of eliminating the deformation of rubber rollers in inserting a shaft and easily positioning the plurality of rubber rollers on the one shaft.

This device comprises a body 11 having a first recessed part 12, a second recessed part 13 connected to the bottom face 12a of the first recessed part 12 and having a diameter smaller than that of the rubber rollers 25 inserted into the first recessed part 12, an air inlet passage 11a opening to the peripheral surface of the second recessed part 13, and a movable stopper 19 projected into the second recessed part 13 from the bottom surface side and varying the distance of the first recessed part 12 from the bottom surface 12a and air supply means 20 to 22 supplying air to the air inlet passage 11a. The rubber rollers 25 are inserted into the first recessed part 12, and the shaft 24 is passed through the hollow parts 25a of the rubber rollers 25 and the tip 24a thereof is brought into contact with the variable stopper 19 while supplying air to the hollow parts 25a of the rubber rollers 25 by an air supply means by closely fitting the insert end face 25b thereof to the bottom face 12a of the first recessed part 12.