CYLINDRICALLY SHAPED BATTERY

The present invention provides a battery that has strength against increase in internal pressure of the battery and does not require consideration of winding displacement in an electrode group. The battery according to the present invention also prevents movement of the electrode group relative to a battery case, and suppresses separation of active materials in plates to prevent deterioration in charge-discharge performance. The battery includes a cylindrical battery case 2 accommodating a positive electrode 31, a negative electrode 32, and a separator 33. The battery further includes an electrode group 3 having a pair of flat outer side surfaces opposed to each other, and a spacer 6 for fixing the electrode group 3. The spacer 6 is disposed between an inner peripheral surface of the battery case 2 and the flat outer side surface of the electrode group 3.