To easily and surely attach a ceiling panel without having irregularity on a product by providing a locking means comprising a decorative cover separately formed in elastic deformation possibility in the axial direction and a groove-like locking part oppositely formed on both the opening ends of a recess for screw stop and engaging both the end edges of the decorative cover.

A ceiling rail 1 disposed at the joining part of a wall panel 10 and a ceiling panel 20 forming a prescribed indoor space forms an attaching part 11 fixed by abutting to the upper end face of the wall panel 10 and a recess for screw stop 12 downward opened adjacent to the attaching part 11 by the extrusion molding or the like of synthetic resin such as vinyl chloride. Furthermore, a groove-like locking part opened so as to be mutually opposed along the longitudinal direction in both the end edge of the opening is formed on the recess for the screw stop 12. A planar decorative cover 2 covering the recess for the screw stop 12 is separately formed of soft resin or the like and the decorative cover 2 is detachably mounted on the locking part 13 provided on the recess for the screw stop 12 by utilizing the elasticity.