Disclosed is a resin composition for an optical material which contains a base polymer (A), a photopolymerizable compound (B), and a photopolymerization initiator (C). Also disclosed is a resin film for an optical material which is made of such a resin composition for an optical material. Specifically disclosed is a resin composition for an optical material which has high transparency and high heat resistance, while enabling formation of a thick film with high precision. This resin composition is particularly useful for a resin film which is used for forming optical waveguides. Also specifically disclosed are a resin film for an optical material using such a resin composition and an optical waveguide using such a resin film.