This article describes the improvement of a pneumatic nutation motor. Pneumatic nutation motors that are driven by diaphragm are expected to have bigger torque. In this report, refined design of the diaphragm is discussed. First, several different shapes of diaphragms are proposed and analyzed with nonlinear FEM. Second, a "bellows type" diaphragm is fabricated and built in the motor. Holding fixture for the diaphragm is also refined to improve its performance. Finally, torques of the new model and conventional model are compared, resulting in that the new model generates the torque 20 percent higher than that of the conventional model at any air pressure.