For vibration control applications, a collocated seneor and actuator is generally desired. In addition, a self-sensing actuator is attractive from the viewpoint of instrumentation minimization. Piezoelectric material is one of promising candidates for the self-sensing actuator because of the reciprocity of its direct and converse effets. However, the method to extract only mechanically induced change from the ourput of piezoelectric materials should be further developed. This paper presents a new self-sensing actuator consisting of an EFPI fiber optic sensor and a piezolelectric ceramic (PZT). By using the PZT as a direction detector, we established a simple and practical phaes tracking logic of the EFPI so that the non-linearity problem of EFPI can be overcome. In addition, the capability of the PZT for the actuator use was also studied. A self-sensing bridge circuit was designed and tested in order to extract direction information from the PZT output while it is commanded by the controller.