Piezoelectric actuators (PA) are widely used in electromechanical system thank to interesting properties such as: high resolution, fast response, wide bandwidth, mechanical simplicity, high stiffness. Despite these unique desirable properties, they suffer from nonlinear behaviors which adversely affect the positioning accuracy. Among them, hysteresis between applied voltage , actuator position is the most important nonlinearity which can lead to significant error if not compensated. In this study, a sliding mode controller associated with an unknown input observer, which uses the position feedback provided by a selfsensing circuit, is suggested to use in micro positioning applications. The selfsensing technique is based on the linear relation between position , charge, which is measured by an active charge measurement circuit. The advantages of proposed scheme could be summarized as follows. It is a sensorless method which does not need an external position sensor. It does not need any operators to model hysteresis or its inverse. It has improved performance in comparison to traditional controllers like proportional integral (PI) controller. Obtained experimental results demonstrate the effectiveness of proposed method to use in micro-positioning applications.