To rationally install a corner panel for constituting a bay window or the like to a reinforced concrete-constructed or steel encased reinforced concrete-constructed building.

When the corner panel 1 is installed at a corner section in the RC-constructed building, an anchor steel bar 2 is inserted into a hole 1d formed along the longitudinal direction on the end-section side in the longitudinal direction of the corner panel 1 while a bolt member 3 is inserted into a hole 1e being approximately orthogonal to the hole 1d and being bored and formed to the rear 1a of the corner panel 1 and a flange section 3a on one end side is engaged with the anchor steel bar 2, and a screw section 3b formed at the other end is projected to the rear 1a side. A metal fitting 4 formed in an L shape is arranged on a slab 5 such as a floor slab, a ceiling slab or the like on the rear 1a side of the corner panel 1, the slab-side piece 4a of the metal fitting 4 is fixed onto the slab 5 by a shooting pin 6, and the screw section 3b of the bolt member 3 projected to a panel-side piece 4b is fixed by a nut 3c.