Provided is a method for producing a nonaqueous electrolyte secondary battery, and a production system therefor, that allow forming a good SEI film in a shorter time. The production method includes an assembly step, an initial charging step and a high-temperature aging step. At least one from among the initial charging step and the high-temperature aging step has the following sub-steps: a step of performing an AC impedance measurement on the nonaqueous electrolyte secondary battery and, on the basis of the AC impedance measurement, calculating an ionic conductivity of an SEI film that is formed the surface of a negative electrode of the nonaqueous electrolyte secondary battery; and a step of determining whether the calculated ionic conductivity falls within a predetermined range or not, and terminating the initial charging step or the high-temperature aging step when the ionic conductivity falls within the predetermined range, and continuing the initial charging step or the high-temperature aging step when the ionic conductivity does not fall within the predetermined range.