A critical mind in this study has begun with the term ‘realizably’ appearing repeatedly in the textbook The Korean Language (Activity) and its curriculum in the elementary education of Korea. A clue of a question about the identity of this term has been gained in the term ‘realization’ appearing repeatedly in Park Mok-Wol’s theory of children’s verse. Thus in his theory of children’s verse, this study tries to illuminate the identity of the term ‘realization’ appearing repeatedly in the elementary Korean linguistic textbook. In this study, the core of Park Mok-Wol’s theory of children’s verse is understood by a ‘theory of realization,’ and its theoretical features and the world of his works are considered synthetically in aspects of the thematic and expressional theories centering around the key word ‘realization.’ This theory of realization has not only fixed firmly a position of children’s verse as poetry but also played an important role in the new development of possibility of the Korean modern children’s verse as a genre. Consequently, Park Mok-Wol’s theory of realization illuminates the identity of the term ‘realizably’ appearing frequently in the elementary textbook The Korean Language (Activity) as well as the children’s literary activities, and shows that the core of realization comes in contact with a question, such as ‘what is poetry?,’ about the foundation of poetic creation and the essence of poetry.