To provide a parking lot structure with roof, which reduces areas required for installing a solar cell panel and utilizes a lot below the roof effectively using support columns to overcome the problem wherein the installation of the solar cell panel is difficult because of restrictions on ensuring adjacent lot in case of offices of a company, factory, store or the like.

This installation method for the solar cell panel with a roof includes the following steps: (A) mounting fittings (1) are attached to the support columns (2), (B) the solar cell panel (3) is attached to a roof board (4), (C) the roof board (4) is mounted with the mounting fittings (1) on the support columns (2), and (D) a mounting angle of the roof board (4) is set in accordance with the optimum direction of daylighting of sunlight, due south direction, and an inclination angle of 30 degrees.