When composers and arrangers compose music, they depend not only on their sense, but also on music theory. Therefore, there is possibility of automatic composition and automatic arrangement by computers. Some studies on automatic composition using computers have been studied continuously for 50 years. For example, an automatic music composition based on counterpoint and imitation using stochastic models and a melody generation method using a tree structure of generative theory of tonal music, are cited as previous studies. In this paper, we propose a method of music interpolation by applying the Wiener filter to scores with missing parts. In addition, we propose a method of music arrangement based on the proposed interpolation method.