We developed an intelligent pneumatic cylinder that realizes positioning servo control using a built-in reflective optical encoder. The developed cylinder is 133mm long, the cylinder's stroke is 40mm, and positioning resolution is 338*m. In this report, we report a new adaptive control algorithm for this cylinder. This algorithm is based on a way that controls switching timing of valve to minimize overshoot of cylinder rod. We compared the adaptive control with servo control from the view point of positioning and convergence speed. We realized high speed positioning control and convergence in any positions, which is difficult for conventional pneumatic cylinders.