Abstract: A battery is provided which includes: an electrode roll having a positive-electrode plate, a negative-electrode plate and a separator interposed therebetween; a battery casing accommodating the electrode roll; and a sealing plate laser-welded to an open end of the battery casing. On the outermost periphery of the electrode roll is located an electrode-base-exposed portion of either one of the positive-electrode plate and the negative-electrode plate. The sealing plate is laser-welded to the battery casing in a state that a collector tab formed by incising the electrode-base-exposed portion and folding the incised portion is held between the periphery of the open end of the battery casing and the sealing plate. With this construction, the electrical connection between the collector tab and the battery casing is assuredly achieved simultaneously with the sealing of the battery to suppress a reduction in the closed-circuit voltage and an increase in the internal resistance.