PURPOSE: To provide an easy fixing system which requires a smaller number of parts and no adjustment by nipping a guide shaft and a sleeve together in the recess of a rocking arm to fix them.

CONSTITUTION: A pin tracter 1 is fitted with a tractor door 16, frame 17 for guiding the travel of continuous paper, frame 19 for supporting the tractor door 16 in such a manner as to allow the door 16 to open and close, paper guide 20, toothed belt 21, and a rocking arm 22 for fixing the pin tractor 1 in a desired position along the width of the continuous paper. The frames 17 and 19 are fixed integrally by screws 23 and 24, and the rocking arm 22 is rotatably fitted to the frame 19 through a shaft ring 25 by a screw 23. The rocking arm 22 is provided with a grip portion 22a and a wedge-like recess 22b of a wedge angle θ, the recess 22b fitted over a guide shaft 2 through a notch 7a formed in the sleeve.