In this paper, a simple piezoelectric floating mass transducer (PFMT) for implantable middle ear hearing devices (IMEHDs) is proposed and its modeling and designing are studied. The transducer which can be implanted in the meddle ear consists of a PMN-PT multi-layered piezoelectric actuator, an elastic material, and a metal case. The proposed transducer has a simple structure and the force generated from the piezoelectric actuator is efficiently transferred to the ossicles of the middle ear. For the analysis of the vibration characteristics, the transducer attached on the ossicle is simplified into a simple mechanical model considering the mass of an incus. And the vibration displacement of the model is calculated using computer simulation and verified by the experimental results. It is shown that the designed PFMT can allow implantation in the middle ear cavity and provide a sufficiently high output of more than 100 nm of vibration displacement. Plus, it is verified that the vibration characteristics of PFMT can be controlled through adjustment of the metal case size and the elastic material of the transducer.