A fastening system which fastens solar cell modules to an installation surface, each said solar cell module having a top surface at which a solar cell substrate is provided, a bottom surface at the opposite side to said top surface, a first side part, and a second side part at the opposite side to said first side part, said fastening system which fastens a plurality of said solar cell modules which are arranged consecutively, comprising: a plurality of support members which abut against said first side parts or said second side parts of said solar cell modules, said plurality of support members supporting said bottom surfaces, said first side parts, and said second side parts of said solar cell modules, and fastening members which prevent at least vertical movement of said solar cell modules with respect to said top surfaces, said fastening members being movably attached to said plurality of support members so that the lock against movement of said solar cell module can be released, wherein said support members support said bottom surfaces of said solar cell modules which adjoin each other across said support members and one said first side part and another said second side part among said adjoining solar cell modules, and said fastening members prevent movement of both adjoining solar cell modules in a vertical direction with respect to the top surfaces of said solar cell modules, characterized in that said fastening members are attached to said support members to be able to rotate about axes parallel to said first side parts and said second side parts, and wherein said fastening members are provided with first engagement pieces which abut against the top surface of one of said solar cell modules which adjoin each other across said support members and second engagement pieces which abut against the other top surface. a plurality of support members which abut against said first side parts or said second side parts of said solar cell modules, said plurality of support members supporting said bottom surfaces, said first side parts, and said second side parts of said solar cell modules, and fastening members which prevent at least vertical movement of said solar cell modules with respect to said top surfaces, said fastening members being movably attached to said plurality of support members so that the lock against movement of said solar cell module can be released, wherein said support members support said bottom surfaces of said solar cell modules which adjoin each other across said support members and one said first side part and another said second side part among said adjoining solar cell modules, and said fastening members prevent movement of both adjoining solar cell modules in a vertical direction with respect to the top surfaces of said solar cell modules, characterized in that said fastening members are attached to said support members to be able to rotate about axes parallel to said first side parts and said second side parts, and wherein said fastening members are provided with first engagement pieces which abut against the top surface of one of said solar cell modules which adjoin each other across said support members and second engagement pieces which abut against the other top surface.