The objective of this article is to make the system of the Korean dialectology. Korean dialectology consists of 7 fields of study; (1) a study of dialect division, (2) a study of individual dialect, (3) a contrastive study of dialects, (4) a study of contract dialect, (5) a study of dialect differentiation, (6) a dialect geographical study of dialect, and (7) a comparative study of dialect. Among these, (2) is divided into three sub-filds of study; (2a) a study of social dialect, (2b) a synchronic study of regional dialect, and (2c) a diachronic study of regional dialect. (1), (2), (3), and (4) belong to the synchronic dialectology which studies the dialects horizintally. (2c), (5), (6), and (7) belong to the diachronic dialectology which studies them vertically.