This invention provides an optical disk device in which heat generated from an optical head and circuit board is dissipated without introduction of outside air or use of a fan. A through portion is provided in part of the mechanical block or outside of the portion on which a tray is projected for carrying a disk for reproduction or write, such that it extends from a disk side portion with respect to the tray to a portion opposing the disk with respect to the tray, in order to introduce air flow generated by disk rotation to an optical head and circuit board and dissipate heat generated at the time of recording or reproduction.