An electrical wire includes a conductor and an insulating layer that covers the conductor and that is cross-linked. The insulating layer is a cross-linked product of a resin composition including (a) a base polymer containing polyolefin and a compatibilizer, (b) a photoradical generator of 0.5 parts by mass or more and 3 parts by mass or less relative to the 100 parts by mass of the base polymer, and (c) a reactive monomer of 1 part by mass or more and 5 parts by mass or less relative to the 100 parts by mass of the base polymer. A relative dielectric constant of the insulating layer is less than 2.5.