The present invention provides an optical disk apparatus which has a cover to cover and uncover an objective lens provided in an optical pickup, thus preventing the objective lens from being contaminated with dust, etc. The optical disk apparatus includes an optical pickup conveying a cover conveying body, and a cover body which actuates the cover. The optical disk apparatus further includes an objective lens protective unit comprising a rack and pinion assembly for operating the cover In the optical disk apparatus of the present invention, the objective lens protective unit is operated by a rotation of the drive motor to move the cover, thus covering and uncovering the objective lens. Therefore, the objective lens is efficiently protected from outside dust.