Provided is a coating liquid which can easily form a porous film having desirably controlled thickness by the method used for a usual semiconductor process, and having an excellent mesopore channel structure. Specifically provided is a composition for forming porous film comprising a surfactant, an aprotic polar solvent and a solution comprising a polymer formed by hydrolysis and condensation of one or more silane compounds represented by foramula (1): RnSi(OR').sub.4-n. Also provided is a method for manufacturing a porous film comprising steps of applying said composition so as to form a film, drying the film and transforming the dried film to a porous film by removing said surfactant. The porous film obtained from the composition for forming porous film is further provided.