Negotiating curves at speeds higher than normal is desired. For the purpose of improving the riding comfort, an active tilting system for railway cars is studied. This system is composed of a curve detector, curve data memories, microcomputers for making control signals, feedback circuits of swing angles, and air servo mechanisms. The whole construction of the system, the method of detecting the entrances of curved tracks, the contents of the objective control signals made by microcomputers, the criteria of the riding comfort, and the system optimization through the running tests are described.