The present invention provides a 
zeolite sol which can be formed into a 
porous film that can be thinned to an intended thickness by a method used in the ordinary 
semiconductor process, that excels in 
dielectric properties, adhesion, film consistency and 
mechanical strength, and that can be easily thinned; a composition for film formation; a 
porous film and a method for forming the same; and a high-performing and highly reliable 
semiconductor device which contains this 
porous film inside. More specifically, the 
zeolite sol is prepared by hydrolyzing and decomposing a 
silane compound expressed by a general formula: Si(OR1)4 (wherein R1 represents a straight-chain or branched 
alkyl group having 1 to 4 carbons, and when there is more than one R1, the R1s can be independent and the same as or different from each other) in a conventional 
coating solution for forming a porous film in the presence of a structure-directing agent and a basic catalyst; and then by heating the 
silane compound at a temperature of 75° C. or lower. A composition for forming a porous film which contains this 
zeolite sol is used.