An optical waveguide photosensitive resin composition containing an aliphatic resin having a polymerizable substituent and a photopolymerization initiator, in which the aliphatic resin having the polymerizable substituent is formed of a side-chain polyfunctional aliphatic resin (A) and a bifunctional long-chain aliphatic resin (B), is provided. Accordingly, the composition brings together high transparency, satisfactory roll-to-roll compatibility, and a high resolution patterning property, and has excellent reflow resistance. Therefore, the composition is useful as a material for forming an optical waveguide, especially a core layer-forming material.
