Method, manufacturing method, and design system for progressive power lens

Provided is technology that makes it possible to design a progressive power lens appropriate for visual behavior of a subject. A method for designing a progressive power lens includes: a step (a) of determining a relationship between a line-of-sight passage position on a surface of a progressive power lens through which a line of sight of a subject wearing the progressive power lens passes and a reactive accommodation amount that the subject exhibits when the line of sight passes through the line-of-sight passage position, based on visual behavior of the subject; a step (b) of judging whether or not the reactive accommodation amount is within an appropriate range; a step (c) of determining a correction method for correcting the progressive power lens based on a result of judgement made in the step (b); and a step (d) of correcting a design of the progressive power lens based on the correction method determined in the step (c).