PURPOSE: To dispense with that a worker climbs on a tower to perform the attachment and detachment of a wire to a swivel device, and allow the worker writing on the ground or on a working base on the ground to perform the wire attachment and detachment to the swivel device in that position.

CONSTITUTION: A boring swivel device has a fixed part 20, a rotating part 30 rotatably connected to the fixed part 20, and an engaging and disengaging raising and lowering member 40 capable of being engaged and disengaged to the fixed part 20, and the fixed part 20 is formed to have a reversed truncated conical outer circumferential side surface in which the outer circumferential side surface 200 of its body 201 is gradually narrowed in diameter from the upper part to the lower part. The member 40 is formed into a cylinder or ring, and the inner circumferential surface is formed in such a manner that the diameter is gradually reduced from the upper part to the lower part with the same gradient as the outer circumferential surface gradient of the body 201. The member 40 can be fitted onto and engaged with, or separated from the body 201 by relatively rising and lowering to the body 201.