Abstract: The present invention relates to a method for converting data in an optical disc drive. In one embodiment of the present invention, data corresponding to a first file system are generated based on file system information collected with respect to data recorded in an optical disc, the generated data are stored in a memory, while first data converted according to the first file system for directories and files recorded in the optical disc, second data for the directories, and third data for the files being stored in the memory separately from each other; information requested from a host is processed based on at least part of the separately stored data and the information is sent to the host. Therefore, an optical disc drive can be used for an AV device with an USB input. Also, data requested by a host are searched quickly and sent to the host.