Provided is an electromechanical transducer to be detachably attached to an electronic device, the transducer including: first and second plates; a rotor rotating around a rotating shaft supported by the plates; a fixed substrate disposed between the plates and facing the rotor; a charged portion having sub-regions disposed on the rotor at intervals in a rotating direction thereof so as to face the fixed substrate; an opposing electrode disposed on the fixed substrate so as to face the rotor; an adjusting unit for adjusting sliding properties of the rotating shaft, the adjusting unit being provided for at least one of the plates; and a gear train coupled to the rotating shaft. The gear train transmits motive power generated by the rotor rotated by electric power of the electronic device to the electronic device or transmits motive power generated by a change in orientation of the electronic device to the rotor.