A micro-actuator of the invention includes a support base having two actuator side arms and a rotatable bottom plate positioned between the actuator side arms; wherein at least one of the actuator side arms having a back-turned extension in a first end thereof; a pair of connection elements that connects the rotatable bottom plate to the actuator side arms in a second end thereof, respectively; at least one PZT elements bonded to the actuator side arms in its length and the back-turned extension. The rotatable plate rotates in a first direction when the at least one PZT elements expand, and a second direction when the at least one PZT elements contract. The invention also discloses a HGA and disk drive unit with such a micro-actuator.