To easily position drilling by a drill meeting with the type of a rail, when a bolt insert hole is drilled on the height position different due to the type of the rail.

A positioning slide plate 11 is elevatably provided on the outside face of a rail pinchedly holding side frame 10 intergratedly connected with a drill fitting side frame 1. The positioning slide plate 11 is provided with a scale board 13 having scales 13A displayed by distinction of the type of a rail 16 so that a drill 5 is on the drilling position meeting the rail 16 when the lower end of the slide plate 11 is placed out the pedestal 16A of the rail 16 at drilling. A guide plate 15 connected to the outside face of the rail pinchedly holding side frame 10 is provided out the outside face of the positioning slide plate 11. A pointer part 15A indicating the scale 13A of the scale board 13 is provided on the guide plate 15.