PURPOSE: To make it possible to add sounds of an optional time length to a still picture or the like by forming a video track group, where videos are recorded, and a sound track group, where only sounds are recorded, on a disk independently of each other.

CONSTITUTION: A disk 1 consists of a circular plane plate-shaped substrate and is provided with a spindle hole 1a in the center. A video track group 2a where still pictures are recorded on concentric circles is formed on the outside circumferential part of an information recording track group 2, and a sound track group 2a where sounds are recorded spirally is formed on the inside circumferential part of the track group 2. Thus, sounds of an optional time length can be added to a still picture or the like.