A head arm assembly (HAA) includes a head slider having at least one head element, an arm member for supporting the head slider at one end section, an actuator, mounted to the other end section of the arm member, for rotationally moving the arm member in a direction substantially parallel with a recording medium surface around an axis for horizontal rotation of the arm member, and a load generation unit for generating a load for energizing the head slider in a direction to the recording medium surface by rotationally moving the arm member in a direction substantially orthogonal to the recording medium surface around an axis for vertical rotation. The position of the center of gravity of the HAA is located at a different position from the axis for vertical rotation on a center axis of the arm member.