Trees are one of the most important elements of natural landscapes. Therefore, in computer graphics, there is a great demand for methods to realize the natural representation of trees in virtual landscapes in various fields such as entertainment industry or environmental assessment in construction. Many studies have been made on techniques in which the shapes of trees are modeled but only a few studies have been reported on methods to incorporate the shapes with motions in a wind field. Most of these studies use physical simulation techniques based on the equations of motion to generate the branch motions and cannot realize the motions of individual leaves. In this paper, we propose a method to create the natural motions of individual leaves and branches swaying in a wind field. This method generates the leaf and branch motions based on "1/f ^\beta noise", which is observed in various natural phenomena. For the branch motion, a simple simulation method based on the spring model is applied to enhance the realism of the motion. This method enables the real-time creation of the leaf and branch motions. Diverse motions according to tree species and shapes and wind conditions can be easily realized by controlling the parameters.