To improve workability by sticking a seat to structural angles of a formwork, and supporting a sleeve spanning between a pair of structural angles by a locking part projected on the seat material.

A fixture 10 comprises a seat material 6 where a semicircumference-like locking part 1 for locking a sleeve port of a sleeve 20 is projected on the surface thereof, and a band material 5 for strapping the sleeve port 21 on the locking part 1. The seat 6 is formed by a resin-made circular seat material a size larger than the sleeve port 21, and the back 6b is a pressure sensitive adhesive surface. In the case of using the fixture 10, a pair of fixture 10 are stuck opposite to an opposing shape 31 for a beam. Next, the sleeve 20 is installed on the locking part 1, and the band material 5 is laid to engage both end hook parts 5a with engagement holes 1a of the locking part 1, thereby fixing the sleeve 20. Thus, arrangement of bars is performed in the formwork, construction can be accomplished easily even in a narrow space, and even if the sleeve is short, it is supplemented by the locking part to prevent concrete from flowing into the sleeve, and facilitate locating.