The libraries of the various learning institutes in the Yi Dynasty may be categorized into four types: 1) The Hyang-Gyo library(the public school libraries in rural districts) 2) The Sabu-Hankdang library (the public school libraries in the Capital) 3) The $Sar{o}war{o}n$ library (the libraries of private learning institutes) 4) The $Jyon-Gyar{o}ng-Gak$ library (the library of the Sung Kyun Kwan which was the highest learning institute in the Yi Dynasty) For the historical study of Korean libraries as well as its education and culture the Hyang-Gyo libraries hold an very important position, but undeservedly its study has been neglected. In this paper, the writer made an effort to grasp the various function of the Hyang-Gyo libraries with its historical background.