Abstract: A method of selecting pneumatic devices that satisfy specified load, speed and strength conditions to construct a pneumatic system. Data concerning pneumatic actuators, solenoid-controlled selector valves, drive controllers, pipes, pipe joints and exhaust treatment devices is stored in a pneumatic actuator database, a solenoid-controlled selector valve database, a drive controller database, a pipe database, a pipe joint database and an exhaust treatment device database, respectively, for each item number, and conditions required for pneumatic devices constituting a system are calculated. Then, pneumatic devices conforming to the calculated conditions are selected from the respective databases. At the first step, a pneumatic actuator satisfying a load condition, a strength condition and a speed condition is selected from the pneumatic actuator database on the basis of a calculation according to a basic equation.