An apparatus for holding a plurality of solar cell units includes a mounting member to be fixed onto a roof, a plurality of fixtures, and a frame member having to-be-sandwiched portions to be sandwiched and fixed between the mounting member and the fixtures, and grooves that support the ends of the plate-shaped solar cell units. The to-be-sandwiched portions of the frame members are positioned inside projection plane regions that project the solar cell units and the grooves immediately below, whereby the distance between adjacent solar cell units reduces.