To provide a bus duct to which oilproof and dustproof countermeasures are performed in addition to a waterproof countermeasure which is examined from a conventional case, and to provide a structure for connecting the bus duct.

In the bus duct, boxes in almost U shapes are bonded to confront each other and a plurality of conductors are stored in a space formed by the confronted boxes. The box arranged above includes an upper surface part where a gradient is formed in a width direction of the box and a side formed by extending downward from an end in the box width direction of the upper surface part.