<p>A joining structure for panels is characterized in that panels are formed so that each panel is provided with a quadrangular panel main body, support pieces formed in opposite sides of the panel main body through bent step portions, and cover pieces formed in the remaining sides of the panel main body, and the panels are joined together such that with the panels disposed longitudinally and transversely, the support piece of one of the panels longitudinally and transversely adjacent to each other has the cover piece of the other panel placed thereon.</p>
