A pneumatic servo seems to be effectively applied to many varieties of gripping or compressing work, because its high compressibility is useful to the force control. In a force control system, the characteristic of the object is comprised in a closed loop, so its influence has to be considered in the design of the controller. However, it is generally unknown and often changes during operation. In particular, the characteristics of the plant changes significantly, when the object is moving. To cope with these problems, more intelligent control schemes are required. In this paper, we propose a design scheme of a model reference adaptive control for a force control system with pneumatic servo. The effectiveness of the proposed design scheme is confirmed by experiments using an existent pneumatic servo system.