A data processing device and a data processing method that can readily process control data having its PAPR improved. In a transmission device a padder pads control data necessary for demodulation with zeros as dummy data and a scrambler scrambles the padded control data (post-padding control data). A replacement unit replaces scrambled dummy data in the scrambled post-padding control data with the dummy data and a BCH encoder and an LDPC encoder perform BCH encoding and LDPC encoding as error correction encoding on the replacement data obtained through the replacement. A shortening unit performs shortening by deleting the dummy data contained in the LDPC code and puncturing the parity bits of the LDPC code. The device can be applied in cases where control data is subjected to error correction encoding and is then transmitted for example.