A roof unit is constructed in such an arrangement that a plurality of combination solar battery and roof panels (103), each having flanges at two opposite sides, are placed adjacent to each other with clearance on a joining/fixing member (105), the adjacent combination solar battery and roof panels are fixed to the joining/fixing member (105) in the clearance by a removable fixture (104), and a removable cap (107) is placed in an upper part of the clearance. This arrangement simplifies the work at a working site, decreases the construction cost, and decreases work errors. In addition, measurement or replacement of each module can be made even after mounted, thus providing a practical vertical-roofing roof excellent in maintainability and also in wind endurance.