An electronic component unit of a wire harness includes a substrate on which an electronic component is mounted, a connector electrically connected to the substrate, and a connector fixing structure. The connector fixing structure includes a pair of notches that are provided facing each other on ends of the substrate in a long-side direction and that penetrate through the substrate in a plate thickness direction, a pair of press fitting plates that are provided on the connector and that are press-fitted into the respective notches, and a deformation acceptable space that is provided adjacent to each of both sides of the press fitting plates press-fitted into the respective notches in the long-side direction.