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 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 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 , wherein the rib includes a flat plate-shaped main rib projecting downward from a side edge of the body , the main rib being inserted from above between the side wall 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 corresponding to an end of the partition rib , and wherein a gap (G) 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 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 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 , wherein the rib includes a flat plate-shaped main rib projecting downward from a side edge of the body , the main rib being inserted from above between the side wall 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 corresponding to an end of the partition rib , and wherein a gap (G) is provided between the first projection and the rib . <EOS>