To easily perform a thermal caulking by simplifying the structures of a caulking main body and a member to be caulked which is fixed by the thermal caulking.

This thermally caulking member is constituted of the caulking main body and the member 20 to be caulked. On the surface of the caulking main body 10, a cylindrical insertion protuberance 11a, which can be thermally caulked, is projected. Also, a guide protuberance 11b, which extends from the lower end of the insertion protuberance 11a along the surface of the caulking main body 10, is provided. Also, an insertion protuberance-inserting section 21a, in which the insertion protuberance 11a is inserted, is provided on the member 20 to be caulked. At the same time, a guide protuberance fitting section 21b, which is connected with the insertion protuberance-inserting section 21a, is provided. The guide protuberance fitting section 21b is fitted on the guide protuberance 11b.