In an actuator 11, which includes a driver 10 including: a substrate 1 having a predetermined width and a predetermined length when viewed from the direction of thickness of the substrate; a reinforcing member 2 provided on one of the thickness-wise faces of the substrate 1; and displacement means (a piezoelectric element 3), provided on the other thickness-wise face of the substrate 1, for displacing, with respect to one of the lengthwise ends of the substrate, the other lengthwise end in the direction of width of the substrate, the reinforcing member 2 is configured so that the flexural rigidity thereof in the substrate's width direction is lower than that in the substrate's thickness direction.