To provide a drive device, equipped with an electro-mechanical converting element whose number of parts used is small and whose structure is simple.

A drive device (actuator) 10 consists of a piezoelectric element 11, a driving shaft 13 and a moving member 14 which friction-combes with the shaft 13 at the fiction combining part, and an extended part 14b is formed at the moving member 14. The extended part 14b is engaged with a groove in an acting member 15 and is brought into pressure contact with the acting member 15 by an energizing spring 16. The pressure contact force is set, so as to be sufficiently larger than the force for moving the moving member 14 in the axial direction. The moving member 14, including the friction combining part and the extended part 14b, is constituted of a single member. A protrusion is formed at the friction combining part so as to bring it into contact with the driving shaft 13, which brings into contact with the driving shaft 13 and the friction combining part each other. By forming this device out of a single member, it is thus possible to reduce the number of parts for a simple its constitution and attain smooth driving by the protrusion.