PURPOSE: To decrease the number of function keys, to improve the operability, and to simplify an operating mechanism by providing a disk drive mechanism and a track ball operating mechanism to a part of the operating mechanism which operates an optical head mechanism, etc.

CONSTITUTION: An operating part 12 consists of two changeover switches 13a and 13b and a control operating mechanism 14. The mechanism 14 uses a track ball operating mechanism 15. This mechanism 15 consists of a rotary ball 15a, an X-direction revolution detector, and a Y-direction revolution detector and is connected to an encoder. Then the switch control is secured among such control circuits for the pause, track search, fast forward, fast rewind and repeat operations, etc., by means of the output of the encoder that is obtained with revolution of the mechanism 15. As a result, various types of switch control are attained with use of a small number of operating members. Then the operability is improved and the cost is reduced with simplification of the constitution for a disk drive device.