Embodiments of the present invention help to provide a magnetic disk drive that is capable of reducing a time period necessary for positioning a magnetic head when positioning the magnetic head by use of a dual-stage actuator. According to one embodiment, a main control circuit of a magnetic head device selects one of a seek mode and a positioning mode. The seek mode is to set a coarse adjustment control system to be a stable system by not causing control of a piezoelectric actuator to be performed by a fine adjustment control circuit. The positioning mode is to set the coarse adjustment control system to be an unstable system and setting a total control system inclusive of the coarse adjustment control system and a fine adjustment control system to be the stable system by causing the control of the piezoelectric actuator to be performed by the fine adjustment control circuit. Thereby the main control circuit causes the control system to operate.