The purpose of this study was to develop a lesson plan for creating music class in elementary school using GI(group investigation) model and examine its effect in a bid to improve problem-solving ability and musicianship. After learning contents that were expected to be appropriate for the application of GI model were selected from the creating activity of the music curriculum for grade 5, a instructional model of creating music was prepared on the basis of Sharan's instructional model. and then a sequential lesson plan was constructed. The subjects in this study were 35 fifth graders from G elementary school in Seoul, where the researcher has taught music classes. The experimental teaching was observed and the students were interviewed to determine the effect of GI-based music classes. To see if there were any changes in their music ability, musical interest and social learning capabilities, worksheets, music notes, group process evaluation, peer evaluation form, music journal and group journal were investigated, and the observation journal made by the researcher, video tapes and a colleague teacher's observation record were reviewed to find out the effect of the creating music. The findings of this study were as below: First, they came to have a better understanding of the music concepts, like rhythm melody and form, and were able to perceive these concepts more keenly. As a consequence, the ability to improvise music improved, and they were capable of composing a short melody. Second, performing ability got better while being engaged in group inquiry using different instruments. Third, when they fulfilled the given task in group. they found it delightful to present their work and put the finishing touches on it within their groups. They became more interactive and alert in the class and they showed bigger interest in music. Fourth, the GI model gave an opportunity for them to play a specific role suitable for each of them and play different instruments. And peer teaching was facilitated and their social skills improved, as they praised, encouraged and gave consideration to one another. Fifth. when they were jointly engaged in group inquiry to work on the given assignments, their composing and performing ability got better, and their problem-solving ability also advanced in the middle of studying how to perform the composition better. Sixth, they acquired a higher reflective thinking when they shared their ideas, made and modify songs in group. and listened to and assessed the other groups' performance. Finally, creating music by GI model can be applicable to music class in the elementary school.