To reduce the thicknesses of a piezoelectric linear actuator, a piezoelectrically driven valve, and a flow rate control device. A piezoelectric linear actuator 1 is provided with: a laminated piezoelectric actuator 2; a bottom supporting member 3 supporting the laminated piezoelectric actuator 2 and extending laterally to the left and right of the laminated piezoelectric actuator 2; a pair of displacement transmission members 5 extending along both the left and the right of the laminated piezoelectric actuator 2, intersecting with the bottom supporting member 3 so as to be vertically movable, and transmitting a displacement due to the piezoelectric effect of the laminated piezoelectric actuator 2; and an output portion 8 locked to the pair of displacement transmission members 5 on the lower side of the bottom supporting member 3 and connecting the lower ends of both the displacement transmission members 5 to each other. Each of the displacement transmission members 5 has an arc-shaped inner circumferential surface along the outer circumferential surface of the laminated piezoelectric actuator 2 and is formed to an elongated member shape having a side wall lying along the arc-shaped inner circumferential surface. At the lower end of the respective displacement transmission members 5, vertically long guide holes 5a into which the bottom supporting member 3 is inserted are formed so as to face each other. The output portion 8 is locked to the lower-side inner peripheral edge portions of the guide holes 5a. The output portion 8 is provided with: a columnar portion 8a, the upper end of which is inserted between the lower ends of the pair of displacement transmission members 5; and a pair of arm portions 8b formed on the outer circumferential surface of the columnar portion 8a so as to project along the bottom supporting member 3 and locked to the inner peripheral edge portion on the lower side of the guide holes 5a of the pair of displacement transmission members 5. The width dimension of the pair of displacement transmission members is formed so as to be the same or the substantially same as the width dimension of the laminated piezoelectric actuator.