This invention provides a battery including a cylindrical battery case and an electrode group that is smaller than the battery case and is accommodated in the battery case, so as to effectively utilize the configurations of the battery case and the electrode group and achieve reliable contact between one of electrodes in the electrode group and the battery case. The battery includes a cylindrical battery case 2 and an electrode group 3 including a positive electrode 31, a negative electrode 32, and a separator 33. The electrode group 3 and an inner peripheral surface of the battery case 2 define a space communicated from a top to a bottom, and the negative electrode 32 has a current collecting terminal 321 that extends from the electrode group 3 in a direction away from a center axis of the battery case 2 and is in contact with a bottom surface 2B of the battery case 2.