To provide an optical film having little change in the mass and little foreign matters under high temperature or high temperature and high humidity conditions, and to provide a polarizing plate and a display apparatus hardly causing light leak.

An optical film containing a cellulose ester and an alkoxy silicon compound expressed by general formula (1) or its hydrolyzed polycondensation product by 0.05 to 3 mass% in terms of SiO2 with respect to the cellulose ester is produced by a solvent casting method. The method includes a step of heating a solution prepared by dissolving the cellulose ester and the alkoxy silicon compound or its hydrolyzed polycondensation product, at 80 to 150°C in a sealed container. In formula (1), each of R and R' represents a hydrogen atom or a monovalent substituent, and n represents 3 or 4.