The purpose of this study is to find the syntactic rules in adverbial clauses in early 20th century"s Korean. This paper can be summarized as follows: The basic structure of the ‘n?-gi-da’ adverbial clause is ‘A가 B를 [adverbial clause] n?gida’. The object(B를) is transformed from subject in a adverbial clause. The basic structure accounts for more than half in the distribution of the entire data. The predicate in the ‘n?-gi-da’ adverbial clause can be classified into adjective and verb. The adjective can be classified into ‘judgment adjective’ and ‘feeling adjective’. The psychological verbs are rarely selected as the predicate in the ‘n?-gi-da’ adverbial clause. The psychological verbs are a lot more selected as the predicate in the ‘n?-gi-da’ adverbial clause than they were in the 19th century. In addition more various words appear as the predicate in the ‘n?-gi-da’ adverbial clause. In ‘n?-gi-da’ adverbial clauses, ‘-ke’ adverbial clauses are rarely found compared to ‘-i’ adverbial clauses. In early 20th century, however, ‘-ke’ adverbial clauses increased sharply, from 5 percent to 33 percent.