A data transmitting method, a data recording apparatus, a data record medium and a data reproducing apparatus are provided to disallow the encryption to be easily decoded and keep the secrecy of key information higher. The data transmitting apparatus includes an error correction coding process block. In the block, an input converting circuit operates to perform a logic operation with respect to the information data from an interface circuit 12 according to the key data. The converted information data is sent to an encoder 15 for generating parity data. This parity data is mixed with information data before conversion in a mixing circuit. The error correction coding block operates to send the resulting data to a modulating circuit 17 for modulating the data. The modulated data is recorded on a disk record medium.