Abstract: In a drainage construction for an electrical connection box in which bus bars are accommodated and tabs projecting from the bus bars are, respectively, projected from terminal through-holes of a lower casing of the electrical connection box so as to be connected to a wiring harness, the improvement comprising: the terminal through-holes each including a main section and a drainage section; the main section having a shape substantially identical with a cross-sectional shape of each of the tabs; and the drainage section abutting on the main section so as to increase a width of each of the terminal through-holes.