To reduce cost and improve assembling workability, and also enable application to a high torque guide pipe by forming a work machine abutting member of a plate having fitting parts to both right and left guide pipes at its opposite ends.

An over-winding detector is provided with a work machine abutting member 21 and a suspension mechanism at a pair of right and left guide pipes 17, 17 of high torque type at the front of a leader 12. Both ends of a body 21a of narrow plate extending between both the pipes 17, 17 are bent in a hook shape to surround a side and a back of the pipes 17, 17 to be fitting parts 21b, 21b to the pipes 17, 17. At a center of the member 21, a suspended metal fitting 21c with a suspension mechanism is provided. Accordingly, the member 21 can be easily worked with a relatively thin plate, and can be fitted easily to the high torque guide pipes 17, 17 as well as low torque pipes, and further workability in transportation, disassembly and assembly can be increased with cost reduction.