Onboard friction control system for Tokyo Metro in Japan was developed and already has been equipped to some commercial trains. In order to improve the efficiency of the onboard friction control system, authors propose a new friction control system by detecting yaw moment acting on running wheelset. At first, field running test with commercial train as a preliminary evaluation of the feedback friction control has been carried out, and results show good correlation between tangential force at the trailing wheelset and lateral force at the leading wheelset. Authors propose that strain gauges attached to linkage between bogie frame and axle box can easily measure the tangential force at the trailing wheelset. Finally, repeated running tests show good results that the tangential force at small curve section has settled to threshold level of feedback control.