PURPOSE: To facilitate installation of a wall panel by providing a first joint filler made of elastic material a little to the surface side of base material, and forming a second joint filler a little to the back face of the base material so as to be recessed from the first joint filler.

CONSTITUTION: A plurality of plates 4 such as tiles or stones are neighbored to each other so as to form a base material 1, and a first joint filler 2 made of elastic material such as silicone is formed a little to the surface side of the side end face of the base material 1. A second joint filler 3 of which material is of higher rigidity than that of the first joint filler 2, is arranged a little to the back face side of the base material 1. Next, the first joint filler 2 and the second joint filler 3 are contacted against the side ends of adjoining wall panels A, the step difference between the end parts of the wall panels A is absorbed, and the joint part is formed. Consequently, the joint can be finished quickly and simply.