『kotoba no umi』 was started by Ministry of Education in Meiji 8th year. But, in conclusion, it was completed by Otsuki Humihiko alone. In early stage of Meiji, there was no concept of ‘National Language’, but 『kotoba no umi』 became the base of modern ‘National Language’ in editing way and organization. 『kotoba no umi』 is considered as the base of ‘National Language’ because, first, 『kotoba no umi』 is a dictionary of everyday language. it includes words general people are using daily, not professional words. It’s modern ideology of equity education. Second, it was organized by Pronunciation, Part of speech, Derivation, Definition, Reference, and Noah Webster in reference of dictionary. Webster made norms of American English through dictionary, grammar, spelling, etc. Otsuki Humihiko can be evaluated similarly. Third, the dictionary was editted based on grammar. Especially, it focuses on grammar of colloquial language. Fourth, it used ‘GOJUON sequence’, not ‘IROHA sequence’ that is traditional way of Japan, so that anybody can find lots of information easily.