The purpose of this study is to survey the transition of the type of openings in korean traditional archiectures. To do this, various types of openings at the backside of Daechung of 23 Hyang-Gyo Myung-Ryun-Dangs were investigated. After the classification in some groups according to their types and their periods of constuction, the tasnsition of the type of openings was analysed. Results are as follows. (1) The openings constructed form 16th to 17th century, the earliest form, is a ledged and battened panel window(or framed and ledged panel window) whose mullion is built on the frame of window. It is presumed that these types were widely used before 17th century. (2) The next type is ledged and battened panel window(door) (or framed and ledged panel window) which lacks a mullion. These types were thought to be customed after 18th century. (3) The lastest type, which is appeared from 19th to 20th century, is an characteristic backside opening(ledged and battened panel window or framed and ledged panel window) that among 3 column spacings the central one is enlarged in comparison with the right and left ones. Through this transition pattern of the openings, can be menifested that the trend of 20th century is to enlarge convenience of usage by constuctiong door and eliminating some windows.