A head gimbal assembly includes a slider, a rotatable micro-actuator and a suspension to load the slider and the rotatable micro-actuator. The rotatable micro-actuator horizontally rotates the slider with a central portion of the slider as an axis, which includes a bottom plate to be connected with the suspension, two arm plates symmetrically disposed on the bottom plate with a central portion of the bottom plate as symmetry point and at least one piezoelectric pieces to be connected with the arm plates. Selectively, the amount of the arm plates can be four and four piezoelectric pieces to be connected with the four arm plates, respectively.