A liquid resin composition is provided which satisfies both a tackiness-free requirement and a curing sensitivity requirement for production of an optical waveguide by a roll-to-roll process. An optical waveguide produced by using the liquid resin composition and a production method of the optical waveguide are also provided. The liquid resin composition for the production of the optical waveguide comprises: (A) a (meth)acrylate polymer, as a major component, having a plurality of (meth)acryl groups in its molecule; (B) a liquid thiol monomer having a plurality of thiol groups in its molecule; and (C) a photopolymerization initiator.