This paper aims to clarify the results to date of Ostrom and Hess’s research project, which was meant to systematize the study of knowledge commons, and lay the foundation on it. In this context, research on knowledge commons is intended as the study of shared knowledge resources, and the institutions for governing them. First, a systematic review focusing on 88 documents extracted from 4 databases such as ProQuest is conducted. The results indicate that the approach, which revises the methodology used in the study of the commons focusing on shared natural resources, is being established. Secondly, the implication of the concept “commons” in it is clarified, the position of it in the study of commons is reviewed, its future research direction is proposed.