An assembled battery, comprising: a case in which a plurality of electric cells are accommodated, each electric cells including a body having a flat rectangular paralleleppiped shape, in which an electrode assembly is accommodated, and a cover which closes an upper end opening of the body, the plurality of electric cells being arrayed in line so that their long sides as viewed from above are opposed to each other, and the case including a sidewall (4d, 4e, 4f, 4g) which surrounds the plurality of electric cells; and an abutment member which abuts against top portions of the electric cells accommodated in the case to position the electric cells with respect to the case, wherein the abutment member includes a body which abuts against the electric cells and a rib (7f, 7g, 7h, 7i, 7k) which projects from the body so as to be inserted into the case, characterized in that the abutment member includes a first projection inserted into a first gap defined by the case and the mutually adjacent electric cells so that the abutment member is aligned in position with respect to the case, wherein a length from the body to a distal end of the first projection is longer than a length from the body to a distal end of the rib (7f, 7g, 7h, 7i), wherein the rib includes a flat plate-shaped main rib (7f, 7g) projecting downward from a side edge of the body, the main rib (7f, 7g) being inserted from above between the side wall (4d, 4e) of the case and a short side as viewed from above of respective electric cells arrayed in line, wherein the rib includes a partition rib which is inserted from above between mutually adjacent two electric cells, wherein the first projection is provided at a position of the main rib (7f, 7g) corresponding to an end of the partition rib, and wherein a gap is provided between the first projection and the rib. a case in which a plurality of electric cells are accommodated, each electric cells including a body having a flat rectangular paralleleppiped shape, in which an electrode assembly is accommodated, and a cover which closes an upper end opening of the body, the plurality of electric cells being arrayed in line so that their long sides as viewed from above are opposed to each other, and the case including a sidewall (4d, 4e, 4f, 4g) which surrounds the plurality of electric cells; and an abutment member which abuts against top portions of the electric cells accommodated in the case to position the electric cells with respect to the case, wherein the abutment member includes a body which abuts against the electric cells and a rib (7f, 7g, 7h, 7i, 7k) which projects from the body so as to be inserted into the case, characterized in that the abutment member includes a first projection inserted into a first gap defined by the case and the mutually adjacent electric cells so that the abutment member is aligned in position with respect to the case, wherein a length from the body to a distal end of the first projection is longer than a length from the body to a distal end of the rib (7f, 7g, 7h, 7i), wherein the rib includes a flat plate-shaped main rib (7f, 7g) projecting downward from a side edge of the body, the main rib (7f, 7g) being inserted from above between the side wall (4d, 4e) of the case and a short side as viewed from above of respective electric cells arrayed in line, wherein the rib includes a partition rib which is inserted from above between mutually adjacent two electric cells, wherein the first projection is provided at a position of the main rib (7f, 7g) corresponding to an end of the partition rib, and wherein a gap is provided between the first projection and the rib.