The purpose of this study is to find the syntactic rules in adverbial clauses in 16th century`s Korean. This paper can be summarized as follows : Adverbial endings in 16th century are [-t?s], [-t?rok], [-ke] and [-i]. Bound nouns that make adverbial clauses are [-t?si] and [-t?s]. [-i] was described as a derivational suffix in 15th century, but in 16th contury it should be described as an adverbial ending.. This is because a syntactic function should be more values than a form. In this paper, the syntactic rules are examined in three directions. First, which grammatical informations appear in the predicate of an adverbial clause? Second, is the subject in an adverbial clause the same as the subject in a holding clause? Third, what kind of relation exist between the predicate in an adverbial clause and the predicate in a holdind clause?