Abstract: A pneumatic motor for pneumatic tools includes a cylinder provided therein with a vane wheel. A rotating shaft inserted in the vane wheel is provided with a withstanding member and a tightening member, which can push the withstanding member to move toward the vane wheel and tighten the vane wheel with the rotating shaft for avoiding gap between the vane wheel and the rotating shaft. Thus, when outside driving air pushes the vane wheel to rotate, the vane wheel can synchronously drive the rotating shaft to rotate immediately and truly. By so designing, this invention can solve the problems of the conventional pneumatic motor that is likely to cause starting delay, untrue in power transmission and easy to wear.