Positive and negative electrode plates of a battery include positive electrode units aligned and connected to one another and negative electrode units aligned and connected to one another, respectively. The electrode plates are folded, in a zigzag pattern, alternately in opposite directions at fold portions each being a boundary between corresponding adjacent two positive electrode units and at fold portions each being a boundary between corresponding adjacent two negative electrode units. The electrode plates and a separator are arranged such that an active material layer on the positive electrode units faces an active material layer on the negative electrode units across the separator, and the fold portions face the fold portions across the separator. The length of each positive electrode unit is greater than the length of each negative electrode units in a direction in which the electrode units are aligned, respectively.