An operation for recording a recording signal onto a disk (1) is interrupted, when an amount of signal data stored in a buffer RAM (11) for temporarily storing the recording signal is less than an interruption setting value during performing of the recording operation. Moreover, when the amount of signal data stored in the buffer RAM (11) increases and indicates a resumption setting value, the signal recorded on the disk (1) before interruption is reproduced, and the recording operation is resumed based on the reproduced signal. Moreover, recording properties are detected by the signal reproduced before resumption of recording.