<p>An actuator (34) comprises: an electro-mechanical conversion element (42); a driving frictional member (44) that is mounted onto one side in an extension/contraction direction of the electro-mechanical conversion element; a driven member (46) that is frictionally engaged with the driving frictional member; a fixed frame (40); an elastic supporting member (48) that is mounted onto the other side in the extension/contraction direction of the electro-mechanical conversion element and displaceably supports the other side of the electro-mechanical conversion element with respect to the fixed frame; and a pressing member that presses the elastic supporting member in the extension/contraction direction to maintain the elastic supporting member in an elastically deformed state.</p>
