There are provided an electric cell group of a plurality of electric cells 11 with positive and negative electrode terminals, connecting members for connecting adjacent electrode terminals, and a wiring module assembled to the electric cell group. The wiring module includes a plurality of voltage detection terminals connected to the ends of a plurality of electric wires W for detecting the conditions of the electric cells, a plurality of retainer portions retaining the detection terminals, and interval adjusting device provided between a plurality of adjacent retainer portions for adjusting the intervals between the retainer portions.