Recently, power assisted nursing care systems have received much attention and those researches have been done actively. In such a control system, an actuator and a control valve are mounted on the human body. Designing the system, the size and weight of the valve become serious concerns. The purpose of our study is to develop a small-sized, lightweight and low-cost servo valve for precise control using wearable pneumatic actuators. In this study, a low-cost wearable servo valve that can control the output flow rate by changing the twisted angle of the buckled tube in the servo valve is proposed and tested. The position control system of a McKibben rubber artificial muscle using tested valve and an embedded controller is also proposed and tested. As a result, we confirmed that the tested servo valve can control the flow rate in both supply and exhaust in an analog way. In addition, the pressure control type wearable servo valve is proposed and tested. As a result, the valve can control the output pressure with a bandwidth frequency of 2.2 Hz. Moreover, the estimated cost of the proposed valve can be reduced about 1/100 (9 US dollars) compared with the typical servo valve.