An optical disk apparatus is disclosed which includes a first printed circuit board, on which a first circuit pattern is formed; a rotor, on which an optical disk may be placed, and which is electrically connected with the first circuit pattern; a second printed circuit board, which is stacked adjacent to the rotor on a surface of the first printed circuit board, and on which a second circuit pattern is formed; a sensor unit, which is mounted on the second printed circuit board in electrical connection with the second circuit pattern, and which is configured to sense a rotation of the optical disk; and a support plate, which supports the first printed circuit board and the rotor. In this optical disk apparatus, a separate printed circuit board can be utilized to support the sensor unit, whereby manufacturing costs can be reduced and working efficiency can be improved.