A data-decoding apparatus having bit-detecting section 4. In the apparatus, an RF signal is reproduced from a recording medium and converted to digital data. If the RF signal has a level (amplitude) equal to a comparator level, the bit-detecting section 4 outputs channel-bit data having logic level “0” or “1” in accordance with whether the sum of the amplitudes of the two RF signals respectively preceding and following that RF signal is higher or lower than the comparator level.