Provided is a photosensitive epoxy resin composition for forming an optical waveguide core comprising a resin component and a photocationic polymerization initiator, the resin component comprising an epoxy cresol novolac resin having three or more epoxy groups, a solid bisphenol-type epoxy resin having two epoxy groups, a liquid bisphenol-type epoxy resin having two epoxy groups, and a solid fluorene ring-containing epoxy compound.
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