To perform stable continuous recording of information onto an information storage medium though many defective areas exist.

Information is recorded by the unit of a file on the information storage medium and the access frequency of an optical head is lowered, thereby Contiguous Data Area being a continuous recording area enabling to continuously record information onto the information storage medium is defined. This contiguous data area is set across one of another file recording area already recorded on the information storage medium or a defective area on the information storage medium to set an extent as an information-recording place to an area divided by another file recording area or the defective area on the information storage medium.