PURPOSE: To reduce memory capacity, to contribute to recording and reproducing for long term of hours and to keep the hourly fidelity at recording and reproducing by preventing data from being written in memory in the period of non-signal, and repeating the same non-signal period as that at recording at reproducing.

CONSTITUTION: A data comparator 22 discrimainates whether or not continuous bit block data (for instance, Dn and Dn+1) are coincident, and outputs detection data at L level and H level when they are coincident and when they are dissident, respectively. In case of non-signal state digitized data outputted from an A/D converter circuit 13 keeps L level. Accordingly, when the coincidence is discriminated in the data comparator 22, it is judged to be the non-signal state, and an IC memory 20 stops a writing action. When data reading from the IC memory 20 is resumed, maker data is outputted again; therefore the non-signal period is repeated at reproduction.