This paper presents a melody-rendering method that is based on the generative theory of tonal music (GTTM). A time-span tree can be obtained by analyzing a melody on the basis of GTTM. Our method is an inverse process of GTTM analysis and outputs a corresponding melody when a time-span tree is input. The melody-morphing method is a melody-generation method that is based on GTTM. With this method, it is possible to generate a new variation of melody by calculating the time-span tree of two melodies. However, melody morphing requires the difficult task of preparing another melody similar to the time-span tree of one melody. Our proposed melody-rendering method, however, can directly generate another melody from the time-span tree of one melody. We conducted an experiment to determine the effectiveness of our method, and the results indicate that all music pieces of 30 time-span trees in the GTTM database can be rendered with our method.