The present application provides a method for adjusting spring characteristics of a spring to desired spring characteristics. In the adjusting method of the present application, first, the spring is compressed until a “load-displacement” measurement line obtained by measuring the load applied to the spring and the displacement of the spring meets a “load-displacement” target line determined based on “load-displacement” characteristics of the spring and the desired spring characteristics (S10-S14). Next, the spring is expanded such that the load applied to the spring decreases along the “load-displacement” target line (S18).