To provide a fixture capable of installing, without giving extension power, construction material such as thin stone, seramics and glass in which an undercut hole is drilled, in relation to fixtures used in a construction industry.

The fixture is used for the inner coating material with the undercut hole, has a male screw part and an axis pin with enlarging continuously in a conical shape, fits loosely at male screw part and has almost equal diameter to the maximum diameter of the above-mentioned enlarging part. It has inner diameter capable of stopping at the above-mentioned enlarging part and provide with one ring having a dicontinuous position. And the cylindrical spacer with inner diameter capable of fitting loosely to the above-mentioned axis pin and a nut for screwing at the male part of the above-mentioned axis pin are provided with. In the fixture characterized by placement of a ring, a cylinderical spacer and a nut in order towards the male part of the above- mentioned axis pin, the fixture can be set to the inner coating materials without giving expansion power by opening of ring. Expanding of the ring can be done always in the same condition without skilful setting technique.