A connection module includes a plurality of bus bars that connect positive and negative electrode terminals of adjacent energy storage elements, a plurality of bus bar holding portions that hold bus bars in an insulated manner, and a pitch adjustment portion. The pitch adjustment portion is to be provided across the adjacent bus bar holding portions so as to couple the adjacent bus bar holding portions, and extends and contracts in a line-up direction of the plurality of bus bar holding portions so as to enable adjustment of a pitch between the positive and negative electrode terminals of the adjacent energy storage elements. Each of the bus bar holding portion includes a bus bar housing portion including an isolation wall that keeps the corresponding bus bars apart in an insulated manner. The bus bar housing portion includes, on one side in the line-up direction, a free portion where there is no isolation wall.