According to one embodiment, a first magnetic head is used to record or reproduce data on or from the first disk surface and includes a first two-terminal element including a first positive terminal and a first negative terminal. A second magnetic head is used to record or reproduce data on or from the second disk surface and includes a second two-terminal element including a second positive terminal and a second negative terminal. A current control unit includes a first current terminal which is commonly connected to the first positive terminal and the second negative terminal and a second current terminal that is commonly connected to the first negative terminal and the second positive terminal and can switch a current polarity between the first current terminal and the second current terminal.