This invention relates to a method for producing a transparent composite material comprising a first step of subjecting a synthetic smectite having a number average particle diameter of from 10 to 300 nm and an aspect ratio of from 10 to 300 to organizing treatment with an organic quaternary ammonium salt and/or an organic quaternary phosphonium salt; a second step of mixing the synthetic smectite subjected to organizing treatment and a curable resin to prepare a resin composition containing the synthetic smectite in an amount of 10 to 40 mass %; a third step of curing the resin composition to obtain a cured product; and a forth step of removing the organic volatile components remaining in the cured product. According to the method, a transparent composite material which is flexible and has a low coefficient of thermal expansion can be obtained which is reduced in outgassing at high temperature under vacuum as in vapor deposition of a conductive thin film.