It is aimed to provide a wiring harness excellent in the waterproof performance of a part covered with a water blocking member also under a high temperature environment, a low temperature environment and a cold heat environment. In a wiring harness (10) in which an exposed conductor part (7) of an insulated wire (1, 2, 3) is covered with a water blocking member (8), the water blocking member (8) is a cured product of a composition containing a urethane (meth)acrylate and has two or more glass transition points.