A method of manufacturing a solar cell module comprising pressing a first silicone gel sheet provided on a sunlight receiving surface of a solar cell string and a second silicone gel sheet provided on an opposite side sunlight non-receiving surface of the solar cell string in vacuum to encapsulate the solar cell string with the first and second silicone gel sheets; disposing the sunlight receiving surface side of the first silicone gel sheet on one surface of a transparent light receiving panel and disposing butyl rubber in a picture frame-like shape along an outer peripheral portion of a panel where the first silicone gel sheet is not formed and laying the light receiving panel and the light non-receiving panel or back sheet over each other with the silicone gel sheet-encapsulated solar cell string on the inside, and pressing them at 100 to 150° C. in vacuum to press bond the light receiving surface panel and the light non-receiving surface panel or back sheet to each other through the butyl rubber.