A curing material, having a solubility parameter of 9.4 or more, contains at least a chain transfer agent that contains a compound containing a polyether structure and two or more urethane bonds or two or more urea bonds in a molecule, and a metal-containing compound. A wire harness is manufactured by supplying the curing material to a conductor exposed portion of a wire bundle including a plurality of bundled insulated wires each having a conductor covered with a covering material made of an insulating body, the conductor exposed portion being formed by removing a part of the covering material of the wire bundle to expose the conductor inside; and curing the curing material by irradiating light in a state in which a surface of the curing material is covered with a protective member formed from a resin containing a plasticizer and having light transmissivity, thereby forming a waterproof portion.