The purpose of this study was to investigate the effects of interaction-based musical activities on the developments of young children's music and language abilities. The development of the music ability was depended upon the 2 categories of tonic and rhythm. Also, the development of language ability was depended upon the 3 categories of vocabulary, language comprehension, and language expression. In this study, twenty 4 year old kindergarten children each in Daegu as an experimental group and two comparative groups participated. The experimental group was trained one time a week over a twelve week period by interaction-based musical activities. The comparative group 1 was disciplined for the same times over the same period by the commercial musical program and the comparative group 2 had regular classes. The three groups were given a pre-test and a post-test to check their music and language abilities. Data of the tests were analyzed by ANCOVA. The experimental group showed each higher score of both the 2 categories for the music ability and the 3 categories for the language ability than the two comparative groups. On the other hand, For the music ability as well as the language ability, there was no significant difference in each score of both the 2 categories and the 3 categories between the comparative groups 1 and 2. These results suggest that the interaction-based musical activities of the experimental group are more effective for the developments of the music and language abilities than the musical activities of the comparative groups