An electrical junction box for a motor vehicle including a casing body that contains inner circuit members, an upper cover and a lower cover that are mounted and locked on the casing body, and a wire harness connected to the inner circuit members. The casing body includes a depression section that is provided on an outer peripheral wall of the casing body to define an electrical wire arranging space, and wire harness holding portions that project from the depression section and the electrical wire arranging space. The wire harness holding portion having arcuate inner surfaces that contact an exterior of the wire harness the wire harness being disposed in the electrical wire arranging space such that the wire harness is held in the holding portions.