Recently brittle porous materials such as graphite and advanced ceramics have been used in the fabrication of aerostatic bearings because gas flow through these porous materials can be limited to a small amount. However, aerostatic bearings consisting of these porous materials are prone to cause pneumatic hammer instability. Therefore, it is considered that reducing the parmiability of porous material only near the bearing surface is a very effective means for avoiding pneumatic hammer instability. In this study, the static and dynamic characteristics of aerostatic circular thrust bearings with such a restrained layer near their surfaces are investigated, theoretically and experimentally. Furthermore, the effects of the restrained layer on the bearing characteristics are clarified.