A robust controller design for a micro motion system represented by a piezoelectric bimorph actuator is considered. The dynamic model of the piezoelectric actuator with nonlinear hysteresis is presented. The nonlinear dynamics of the actuator are first linearized using the stochastic equivalent linearization method. Then a robust controller is designed for the piezoelectric actuator system using a state space approach which guarantees stability and good performance of the controlled system. Three approaches are considered. First a suboptimal l H¥controller is designed to provide both robust stability and performance. The results show that the controller do not meet all the design objectives, as it has a very long settling time of 0.18sec. The second approach consists of two parts, a state feedback controller designed to achieve some of the overall design objective (low steady state error and fast response) and an H¥ controller designed to provide both robust stability and better performance. This approach solves the settling time problem (it achieved a 1.8msec settling time), but has a very wide bandwidth (approximately 2´105 rad sec ). This problem is solved in the third approach by adding a model-reference to the state feedback / H¥ controller. This ensures internal stability and satisfies both frequency and time domain requirements, as well as obtaining minimal performance H¥- norm of the closed-loop system. Simulation results of the time and frequency domains responses show that the design is very successful in terms of steady-state tracking error of 1.2% and settling time of 2.55msec, as well as other performance requirements. The hysteresis effects in the positioning precision of the piezoelectric actuator are largely reduced using the H¥ controller from 13.5% to 0.5%.