JPH0766573B

PURPOSE:To enlarge the proper operating range of a producing condition without damaging the reproducing performance of header information by providing no guide groove on a part or all of a section on which the header information is recorded. CONSTITUTION:The guide groove 1 is not provided on the sector mark signal bit part 4 of the header information part 3 of an optical disk and the part 4 forms a specular surface. According to the recording system of the groove 1, it is required to provide groove 1 on a part or all of the part 3 and it is preferable to provide no groove in a part, especially only in the part 3. Accord ing to the recording system of this guide groove, even when the groove 1 is not provided in the part 3, a tracking characteristic is not substantially lowered nor the influence of a groove recording laser beam is present to enlarge the amplitude of the reproducing signal of the part 3. The irradiating condition range of an information bit recording laser for eliminating the inversion of a sector mark reproducing signal can be increased to eliminate a long and narrow hill part between the groove and a pit, thereby, a resin can be easily filled therein.