An electrical junction box facilitates a worker's wiring of a wire harness without using a superfluous component and allows the workability in assembling the electrical junction box as well as that in disassembling to be improved. The electrical junction box includes a box body and a cover to be mounted to the box body after wiring wire harnesses about the box body. The box body has wiring grooves shaped to have U-shaped cross sections and arranged on its exterior surface to accommodate the wire harnesses, which have been drawn out of the box body through its one side and further led from an upper part of the one side downwardly. Left and right sidewalls defining each groove are provided, at their leading ends, with temporary locking parts restricting slipping of the wire harness out of the wiring groove. The cover is provided with restricting walls (sidewalls, rib) restricting outward deflection of the left and right sidewalls. In mounting the cover to the box body, the restricting walls are inserted to the outside of the sidewalls and between the adjoining sidewalls. The restricting walls have withstanding parts formed to prevent the temporary locking parts from being deflected outside.