A film for a membrane structure, which comprises a film substrate containing a fluororesin, a photocatalyst layer and an interlayer interposed between the film substrate and the photocatalyst layer, wherein the fluororesin is at least one member selected from the group consisting of an ethylene/tetrafluoroethylene copolymer, a tetrafluoroethylene/hexafluoropropylene copolymer, a tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer, a polyvinyl fluoride and a polyvinylidene fluoride; the interlayer contains an organic-inorganic hybrid polymer obtained by hydrolyzing/co-condensing at least one member selected from the group consisting of an organosilane, a hydrolysate of an organosilane and a condensate of an organosilane, and a silyl group-containing organic polymer; and the mass remaining ratio of the organic-inorganic hybrid polymer is from 50 to 80% at 500° C. measured by thermogravimetric analysis.