An electrical junction box includes an accommodation box having an accommodation box body having an accommodation space penetrating trough the accommodation box body up and down and an electrical component mounting block inserted into the accommodation space from either upside thereof or the underside and fixed in the accommodation space. The electrical junction box fiber includes a first locking mechanism arranged between an inner wall of the accommodation box body and an outer wall of a block body to lock up the electrical component mounting block inserted into the accommodation space from its upside and a second locking mechanism arranged between the inner wall of the accommodation box body and the outer wall of the block body to lock up the electrical component mounting block inserted into the accommodation space from the underside.