To restrain occurrence of working failure of adjusting work, tightening work, etc., due to magnetization of a tool at the time of using a tightening tool, an adjusting tool, etc., under a circumstance where a magnetic field is generated and to improve workability itself.

A part or all of tools used under a circumstance where a magnetic field is generated, for example, fastening tools and adjusting toolssuch as screwdrivers, wenches, spanners, etc., is or are constituted of a ceramic member 2, for example, various ceramic sintered bodies a fracture toughness value of which is more than 4 MPa.m0.5 and breaking resistant strength of which is more than 400 MPa. As the ceramic sintered bodies, a silicon nitride sintered body, a sailon sintered body, a silicon carbide sintered body, a boron nitride sintered body, zirconia sintered body, tungsten carbide sintered body, a titanium borite sintered body, etc., can be mentioned.