An electronic component unit and a wire harness are provided with a bus bar plate. The bus bar plate is provided with a metallic bus bar that is built in a resin material, and including a through-hole in which a terminal of a relay mounted on a mounting surface is soldered. The through-hole is provided with a bus bar through-hole which penetrates the bus bar, and a resin material through-hole which penetrates the resin material and is formed to be larger than the bus bar through-hole to expose the surface of the bus bar. When an inner diameter of the bus bar through-hole is defined as r and an inner diameter of the resin material through-hole is defined as R, 1.5r≦R is satisfied.