A secondary battery manufacturing method, comprising the steps of: moving mutually opposing rows of guide members with a separator suspended between the rows from a suspension roller, thereby zigzag-folding the separator; inserting positive electrode plates and negative electrode plates alternately into respective folds of the zigzag-folded separator, thereby forming a layered body having the positive electrode plates and the negative electrode plates alternately superposed on each other via the separator; and pulling the guide members out of the respective folds of the separator, and then pressing the layered body in a direction in which the positive electrode plates and the negative electrode plates are superposed, thereby manufacturing an electrode plate group, characterised in that at least one buffer roller (45, 46) is disposed between at least two support rollers (42, 43, 44), the support rollers supporting the separator upstream, in transport direction of the separator, of the suspension roller and upstream and downstream of each other, the buffer roller (45, 46) making contact with one surface of the separator, and being arranged to be ascendable and descendable in vertical direction, with the buffer roller (45, 46) being located at a predetermined ascending position or descending position while being kept in contact with the separator, the separator is suspended between the rows of guide members from the suspension roller, and during the step of zigzag folding by movement of the guide members, the buffer roller (45, 46) descends or ascends, wherein the product of the stroke of each buffer roller during vertical movement and the number of buffer rollers secures the amount of the separator pulled in horizontally by the guide members during zigzag-folding of the separator. moving mutually opposing rows of guide members with a separator suspended between the rows from a suspension roller, thereby zigzag-folding the separator; inserting positive electrode plates and negative electrode plates alternately into respective folds of the zigzag-folded separator, thereby forming a layered body having the positive electrode plates and the negative electrode plates alternately superposed on each other via the separator; and pulling the guide members out of the respective folds of the separator, and then pressing the layered body in a direction in which the positive electrode plates and the negative electrode plates are superposed, thereby manufacturing an electrode plate group, characterised in that at least one buffer roller (45, 46) is disposed between at least two support rollers (42, 43, 44), the support rollers supporting the separator upstream, in transport direction of the separator, of the suspension roller and upstream and downstream of each other, the buffer roller (45, 46) making contact with one surface of the separator, and being arranged to be ascendable and descendable in vertical direction, with the buffer roller (45, 46) being located at a predetermined ascending position or descending position while being kept in contact with the separator, the separator is suspended between the rows of guide members from the suspension roller, and during the step of zigzag folding by movement of the guide members, the buffer roller (45, 46) descends or ascends, wherein the product of the stroke of each buffer roller during vertical movement and the number of buffer rollers secures the amount of the separator pulled in horizontally by the guide members during zigzag-folding of the separator.