Purpose of the study: The purpose of the study was to analyze the grammatical function of the noun of Japanese and Indonesian language and diversification of Noun and the system of inflectional of two language
 Methodology: The methodology of the study was qualitative that focused on library research. In this case, the author conducted constructive analysis to analyze the similarities and differences of the languages in terms of form and function by text-book based on Indonesia and the Japanese Language. The text-book based constructive analysis of library research was chosen to be able to evaluate and renovate the text-book used by language students; Indonesian and Japanese so that their understanding of language comparison and contrast of those languages would be better in the future. Additionally, the lingual contrastive theory was also applicated to establish the term of comparison of the noun of Indonesian and Japanese. From the analysis of the data, it found that the diversity of Noun Forms of Japanese as the subject or the object is classified by particles such as WA,O. A different variation is reflected in the form of the noun of Indonesian where it is not followed with the word of the object.
 Main Findings: This study also found that the equality form of Noun between Indonesian and Japanese in terms of the function of the subject and the object that refers to the name of people, place, etc.
 Applications of this study: The implication of the study is applicated with the process of language acquisition of Japanese as the foreign language of Indonesian students, especially in evaluating and renovating the text-book used by students.