An information processing device is provided. The device includes an upper enclosure; a lower enclosure which supports the upper enclosure with a varied attitude and on which the upper enclosure may be superposed; a disk drive device stored in the upper or lower enclosure and having a disk mounting part on which a disk-shaped recording medium is detachably mounted; and an enclosure moving mechanism setting a disk storage region to have a first thickness with the upper enclosure allowed to have a distance from the lower enclosure when the disk drive device is used and setting the disk storage region to have a second thickness smaller than the first thickness with the upper enclosure allowed to come close to the lower enclosure to reduce the disk storage region when the disk drive device is not used.