An electrical junction box 1 includes: a metallic substrate 24; a relay 25 mounted on a surface of the metallic substrate 24, and arranged lower than the metallic substrate 24; an upper cover 4 covering the metallic substrate 24, and arranged upper than the metallic substrate 24; a hole 17 opening on a surface of a ceiling wall 7 arranged parallel to the metallic substrate 24 of the upper cover 4; and a heat introducing tube 18 continued to an inner edge of the hole 17, and penetrating the metallic substrate 24.