PURPOSE: To attain labor saving and improve work efficiency, by adapting a bolt or nut to be sucked in a socket by means of suction force of an electromagnetic coil and thread-mounted to a work.

CONSTITUTION: A bolt or nut engagement hole 32 is provided in the underside of a socket 24. An electromagnetic coil 34 as suction means is disposed in a manner to encircle the engagement hole 32. On the top face of the socket 24 is provided a terminal plate 36, on which are disposed electrode plates 38a, 38b connected with the coil. On the side of the main body 22 are provided electrodes 40a, 40b whereby the coil 34 is adapted to be excited. If the coil 34 is excited, the socket 24 is magnetized and sucks the bolt or nut in the engagement hole 32 and then the bolt or nut is thread-mounted to the work in the sucked-in state.