indicated by the shaded portions in the figure by correcting errors in data based on this information it is possible to properly decode the data in such a case the data may be recorded a plurality of times fig1 shows another example different from the example of fig1 in which the case where a sync is not properly detected or erroneous data is included in error correcting code for subcode occurs a plurality of times serially and the data between the errors is processed since the data may be erroneous use of such an algorithm increases the reliability of information on the positions of errors in data making it possible to correct the data by discarding the erroneous portions fig1 is a flowchart showing a method for processing the data to be recorded described so far changing the structure of the data first of all when data is recorded it is determined whether the target area is the management area at step 171 and if it is the user data area the data is processed in units of 64k bytes syncs and subcodes are added at step 173 and the data is interleaved to produce a record data structure at step 174 if the target area is determined to be the management area at step 171 on the other hand the size.