The invention provides a miniature actuator in which a plurality of driven members can be driven with common drive friction member and electromechanical conversion element. The actuator 34 comprises a piezoelectric element 42, a drive shaft 44 fixed to the displacement surface 42A of the piezoelectric element 42, coupling pieces 46 and 47 friction-engaged with the drive shaft 44, and presser springs 56 and 57 for biasing the coupling pieces 46 and 47 individually. The presser springs 56 and 57 are composed of a shape memory alloy and when they are heated by means of heaters 66 and 67, the presser springs 56 and 57 deform to regulate the biasing force individually.