A wiring harness has a waterproof structure in which a waterproof agent covers a conductor exposed portion-and outer peripheral surfaces of end portions of wire covering members of a plurality of insulated wires in succession, the portion including a splice portion where portions of the members of the insulated wires are removed and the exposed conductors are spliced together and a bundle of the exposed conductors of the insulated wires, the end portions being adjacent to the portion, whereby the portion is sealed with the waterproof agent, wherein the waterproof agent is a cured product of an ultraviolet curable adhesive agent that contains (A) an ester acrylate having a linear or branched C2-C12 alkyl group, (B) a (meth)acrylate compound comprising at least two urethane bonds in one molecule, and (C) a photopolymerization initiator.