Abstract: A supporting structure (2) that stacks and supports solar cell modules in the horizontal state includes a base portion (23) stacked in the up-and-down direction, a reception portion (28) that supports the corner portions of the solar cell module that are projectingly formed in the lateral direction from the inner side wall surface (23c) of the base portion (23), an engaging convex portion (25) formed on the upper end surface of the base portion (23) and engaged with one of supporting structures adjacently arranged up and down, and an engaging concave portion (26) formed on the lower end surface (23b) of the base portion (23) and engaged with the engaging convex portion of the other of supporting structures adjacently arranged up and down, and wherein the engaging concave portion (26) is opened on the external side wall surface (23d) of the base portion (23).