The present invention aims to provide a polyvinyl acetal resin composition that is moldable by an extrusion method and capable of exhibiting excellent heat resistance after molding, an adhesive sheet containing the polyvinyl acetal resin composition, and a method for producing the adhesive sheet. The present invention relates to a polyvinyl acetal resin composition including: a polyvinyl acetal; a reactive diluent; and a photopolymerization initiator, the polyvinyl acetal resin composition having a storage modulus G′ at 200° C. before irradiation with light of 8×104 Pa or lower and a storage modulus G′ at 200° C. after irradiation with light of 8×103 Pa or higher, with the storage modulus G′ at 200° C. after irradiation with light being higher than the storage modulus G′ at 200° C. before irradiation with light.