There is provided a process of producing a solar battery module including a solar battery cell sealed by a resin between a transparent panel of the light reception surface side and a back face panel, which is characterized in that the sealing resin is made of a crosslinkable thermoplastic resin, a first sealing resin sheet substantially covering the entire surface of the transparent panel of the light reception surface side is arranged between the transparent panel of the light reception surface side and the solar battery cell, a second sealing resin sheet substantially covering the entire surface of the back face panel is arranged between the back face panel and the solar battery cell, the assembly is introduced into a sealing treatment vessel, and the sealing operation including respective steps of a step of reducing the pressure in the sealing treatment vessel at a temperature at which the thermoplastic resin is not melted (step 1); a step in which the temperature is raised to the vicinity of or higher than the melting point of the thermoplastic resin in the reduced-pressure state (step 2); a step in which the pressure in the sealing treatment vessel is raised (step 3); a step in which the temperature is raised to a temperature range where a crosslinking reaction proceeds, thereby proceeding with the crosslinking reaction (step 4); and a step in which cooling is performed (step 5) is carried out.