A wire harness wired to a vehicle has an electrical connection box at a terminal thereof. The electrical connection box includes an electronic component block to which a plurality of electronic components are assembled and a casing to be an assembly destination of the electronic component block. The casing has a structure in which an upper cover rotates and moves to cover an upper opening portion surrounded by an edge of a frame peripheral wall. The casing includes the frame peripheral wall having the upper opening portion, the upper cover covering the opening portion by rotational movement, and a packing to be assembled to the upper cover. The packing is assembled to a packing groove formed in the upper cover. The frame peripheral wall has a position adjusting portion for adjusting the position of the packing groove with respect to the edge of the frame peripheral wall.