A protective device (1) for protecting an optical head (2) of a disc drive unit against dirt and dust and shock when the disc drive unit is not in use comprises a carrier disc (5) similar to a music CD disc for engaging in the disc receiving area of the disc drive unit. A brush member (6) located on the carrier disc (5) at a position corresponding to the inner data track (10) of a music CD disc is provided for engaging a lens (3) and a peripheral portion (7) of a lens carrier (4) of the head (2) when the head (2) is in the inactive position for protecting the lens (3) and the peripheral portion (7) against dirt and dust. Fibers (15) of the brush member (6) embrace the lens (3) when the head (2) is in the inactive position.