The purpose of this paper is to clarify the transformation and the development process of the function of the Ogakumon-jo in the imperial palace. In this study, I tried to indicate the transformation from period of emperor Gonara to Ougimachi, and the development in the period of emperor Gomizunoo. A summary will be given as follows : 1. The Ogakumon-jo came into use as one of the space for the private reception, especially of doctors from the emperor Gonara. 2. The Ogakumon-jo changed into the exclusive space for the reception of doctors in the period of emperor Goyouzei. 3. The Ogakumon-jo developed into the space for the various studies and exercise, at the Keichodo-Dairi in the emperor Gomizunoo. 4. The character of Ogakukmon-jo where was a private space for the emperor was unchangeable.