The present invention provides an optical waveguide excellent in all of transparency, a bending property and heat resistance and a dry film for manufacturing an optical waveguide. A clad layer of the optical waveguide according to the present invention is formed by using a dry film containing a polymer comprising at least a (meth)acrylate monomer with an epoxy group and a (meth)acrylate monomer without an epoxy group; and cationic or anionic curing initiator.