To provide an optical disk recorder capable of reading data currently recorded even if the power supply is turned off during the recording of record data in a system using an optical disk in which table-of-contents information is not recorded in an area other than a user's recording area for recording record data and recording and reproducing of data is controlled according to the table-of-contents information. The optical disk recorder comprises an optical disk constituted so that table-of-contents information is written in an area other than a user's recording area for recording record data, a storage circuit constituted so that data can be read out of or written into the circuit by extending or compressing regenerated or recorded data in order to reproduce or record data from or into the optical disk, and a system controller for controlling reproducing and/or recording of data from and/or into the optical disk and storage circuit, and writes table-of-contents information in an area other than the user's recording area of the optical disk in accordance with a decided command for deciding the table-of-contents information given to the system controller, while recording record data in the user's recording area of the optical disk.