As a tape recording format, tracks are formed by a succession of block units, and a data unit called a group is formed by data of size equivalent to a predetermined plurality of tracks. Using this format, a base group number indicating the group to which the current track physically belongs is recorded in the ID information for a track, and the lower four bits or similar of a group number indicating the group to which the current block logically belongs is recorded within a block. By this means, even if rewriting is performed in block units and a recorded state results in which the blocks of a plurality of groups are intermixed within a track, the group to which each block belongs can be correctly identified during reproduction.