In recent years, there have been lots of attention in the use of membranes for spacecraft applications, as so-called gossamer structures, very large and ultra-light structures, have recognized as the most viable space deployable structures. Typical applications include sunshields, parabolic reflectors. solar concentrators, and solar sails. As for the solar sail, the packing and deployment method of sail membrane play a very important role in the mission. There has been proposed a deployment method that employs the centrifugal force, and various kinds of folding pattern have been proposed to pack the membrane into the small volume. It is now required to establish the evaluation method of the folding pattern as well as the numerical method to analyze the dynamics of deploying membrane. This paper considers the dynamics behavior of a membrane that deploys by centrifugal force, and discusses the evaluation method of the folding pattern. It also discusses the dynamics model of membrane, i.e. mass-spring approximation model.