This paper searches for the chronological significance of newly composed children’s song during the Japanese occupation period, and investigates how the rhythm of lyrics in syllabic-metric pattern and rhythm of melody create a sense of unity in these songs. Also how the necessary characteristics required for children’s song such as simplicity, conciseness, and functionality were achieved through this unity by analyzing these songs. The analyses show a process of finding an answer for reflecting the regularity in the rhythm of lyrics into music when using the rhymed verse as lyrics. In order to find out the coherence of figures consisting melodies of songs, parameters such as pitch rhythm ect. were used as analytical tools. The syllabic-metric pattern of the most of early children’s songs follow usually stereotyped 7·5 pattern, and the pattern’s rhythmic regularity corresponds to that of phrase thus resulting a sense of unity between lyrics and melody. It seems that “simplicity” in these early children’s song is realized through regular reiteration. Homogeneity inherent in similar figures also yield consistency. Uniformity achieved by repeated rhythmic pattern is related to simplicity of melody. Through the analyses, it is also confirmed that the composers of early children’s song follow the traditional western music language such as “repetition” and “contrast” of formal structure. In this point of view, musical form has the order of “presentation- repetition–contrast-recapitulation.” Variation technique is also found in these songs where the skeleton of the melody is maintained while the other elements are transformed and modified.