An apparatus for reading/recording data from/on a recording medium, the apparatus comprising: a pickup configured to read or record data from or on the recording medium; and - a controller, operatively coupled to the pickup, configured to read version information of the recording medium from the recording medium, the version information including first compatibility version information and second compatibility version information usable for determining a possibility of access for reading/recording the data from/on the recording medium; the controller configured to determine the possibility of access for reading/ recording the data based on the first compatibility version information or the second compatibility version information, the possibility of access for reading the data being determined based on the first compatibility version information, and the possibility of access for recording the data being determined based on the second compatibility version information if the access for reading the data is possible based on the first compatibility version information, wherein the access for recording the data is determined to be impossible if the access for reading the data is impossible based on the first compatibility version information, wherein the first compatibility version information is sequentially increased whenever a specification of the recording medium is changed to a range having no read compatibility, the second compatibility version information is sequentially increased whenever a specification of the recording medium is changed to a predetermined range having no write compatibility while the read compatibility is kept. a pickup configured to read or record data from or on the recording medium; and - a controller, operatively coupled to the pickup, configured to read version information of the recording medium from the recording medium, the version information including first compatibility version information and second compatibility version information usable for determining a possibility of access for reading/recording the data from/on the recording medium; the controller configured to determine the possibility of access for reading/ recording the data based on the first compatibility version information or the second compatibility version information, the possibility of access for reading the data being determined based on the first compatibility version information, and the possibility of access for recording the data being determined based on the second compatibility version information if the access for reading the data is possible based on the first compatibility version information, wherein the access for recording the data is determined to be impossible if the access for reading the data is impossible based on the first compatibility version information, wherein the first compatibility version information is sequentially increased whenever a specification of the recording medium is changed to a range having no read compatibility, the second compatibility version information is sequentially increased whenever a specification of the recording medium is changed to a predetermined range having no write compatibility while the read compatibility is kept.