A transmitter comprising: an encoding unit to generate a code word by performing coding with a low-density parity-check code using a check matrix, wherein the;code word comprises information bits and parity bits; the encoding unit being capable of switching the check matrix for use in generating the code word, between a first check matrix with a first code rate and a second check matrix with a second code rate smaller than the first code rate, wherein the first check matrix comprises a first region including information bits of the code word of the first code rate and a second region including parity bits of the code word of the first code rate; the first check matrix containing a plurality of cyclic permutation matrices, the encoding unit generating the second check matrix by masking a cyclic permutation matrix at a predetermined position in the first region of the first check matrix; wherein the masking refers to inverting elements "1" included in the matrix into "0"; wherein the second check matrix includes a third region and a fourth region in addition to the first and second regions (H1, H2); the third region is a region including the information bits of the code word, and the fourth region is a region of parity bits of the code word added so as to satisfy the second code rate; wherein the the third region has the same number of columns as the first region and is located adjacent and below the first region, the fourth region corresponding to additional parity bits is adjacent to the second region and the third region and is located to the right and below the second region, and the third region and the fourth region comprise a plurality of cyclic permutation matrices; wherein the second check matrix is constructed such that the column weights of columns of information bits in the third region and the masked first region are maintained at or below a threshold; wherein the number of the elements "1" included in a column of the check matrix is referred to as a column weight; and further comprising Z a transmission unit to convert the code word into a transmission signal and transmit the transmission signal. an encoding unit to generate a code word by performing coding with a low-density parity-check code using a check matrix, wherein the;code word comprises information bits and parity bits; the encoding unit being capable of switching the check matrix for use in generating the code word, between a first check matrix with a first code rate and a second check matrix with a second code rate smaller than the first code rate, wherein the first check matrix comprises a first region including information bits of the code word of the first code rate and a second region including parity bits of the code word of the first code rate; the first check matrix containing a plurality of cyclic permutation matrices, the encoding unit generating the second check matrix by masking a cyclic permutation matrix at a predetermined position in the first region of the first check matrix; wherein the masking refers to inverting elements "1" included in the matrix into "0"; wherein the second check matrix includes a third region and a fourth region in addition to the first and second regions (H1, H2); the third region is a region including the information bits of the code word, and the fourth region is a region of parity bits of the code word added so as to satisfy the second code rate; wherein the the third region has the same number of columns as the first region and is located adjacent and below the first region, the fourth region corresponding to additional parity bits is adjacent to the second region and the third region and is located to the right and below the second region, and the third region and the fourth region comprise a plurality of cyclic permutation matrices; wherein the second check matrix is constructed such that the column weights of columns of information bits in the third region and the masked first region are maintained at or below a threshold; wherein the number of the elements "1" included in a column of the check matrix is referred to as a column weight; and further comprising Z a transmission unit to convert the code word into a transmission signal and transmit the transmission signal.