Bus bars to be contained in an electrical junction box are secured to insulation plates without caulking. An electrical junction box contains bus bars in a casing. The bus bars are disposed on an inner surface of the casing. Attaching pieces provided on the bus bars are inserted into and secured to receiving apertures provided in the casing. The attaching piece of each bus bar has a rectangular shape in cross section. Each receiving aperture in the casing is a circular aperture or a rectangular aperture. At least a part of an outer peripheral wall of each attaching piece contacts with an inner peripheral surface of each receiving aperture to restrain the attaching piece from moving in the aperture.