Provided is a progressive addition lens (1a, 1b), a manufacturing method and a design method therefor, and a progressive addition lens manufacturing system (10), capable of flexibly adapting to an actual use state of a wearer and optimal for each of the wearer, for determining a main line of sight considering not only convergence of the eye occurring with near vision including passive accommodative power but also convergence of the eye induced by using an accommodative power margin of the eye. The design method of a progressive addition lens (1a, 1b) includes a first main line of sight calculation step (S6) of calculating a first main line of sight, where accommodative convergence caused by use of the accommodative power margin of the eye is considered, based on lens design information including at least information of the accommodative power of the eye of a wearer and a final main line of sight determination step (S7) of determining a final main line of sight (2a, 2b) of a lens from the first main line of sight.