This study aims at developing children`s ability of improvisation by means of play. Most teachers and students identify musical creation with composition. It is clear that many students think that composition is difficult, because they have to know musical notations and many rules of music to compose music. However, improvisation is also a way to show creativity. It is useful for lower-grade students and student who are not competent to compose music. Lower-grade students like play and movements in short time. I developed teaching steps and contents for improvisation, collected and developed various plays needed to apply the teaching steps. I applied the methods to the students in my class. The teaching steps for improvisation consist of four parts: taking interest, learning pattern, improvisation, application and development. In the part of taking interest, students can learn rhythmic sense and interest in melody with play. In the part of learning pattern, students can learn many rhythm patterns and melodic patterns with play. In the part of improvisation, students can improve rhythm or melody with play. In the part of application and development, students can learn reading and writing musical notation for composition. I think that most students in all grades of the elementary school can do improvisation and their musical creativity can be developed with improvisation.