In this paper, H^∞ control theory and μ synthesis are applied to vibration control of active suspension for high speed train. A linear 58th order model is built for the dynamical analysis of the train model. This model takes into account the body, truck frame, wheel, hydraulic actuator, and property of track irregularity. A hydraulic actuator replaces a lateral damper between body and truck frame of the conventional passive suspension train. The controller for vibration control is synthesized by H^∞ control synthesis and improved by μ synthesis. The characteristics and performances of the controllers are examined by performing numerical calculations of frequency response and computational simulations. As a result, it is clarified that the active suspension for highspeed train is effective to improve ride quality and that the present synthesis method is useful.