To provide a data transmitter, a data receiver, a data transmission method and a data reception method by which rate matching processing is always applied to a bit length of a prescribed size thereby preventing the processing quantity from being increased even when number of transport blocks sent through a transport channel and a transport block size are changed.

A CRC attach section 101 through a convolution coding section 103 apply coding processing to transport channel data (TrCH data) for error correction. A DTX(Discontinuous Transmission) bit insertion section 104 inserts DTX bits to fill in a bit number of a difference to the TrCH data when the number of the TrCH data after coding processing has the difference, that is, is less than a predetermined maximum value. A rate matching section 105 decides number of bits for mapping the TrCH data after the insertion with data on a physical channel having a spread rate designated by a host layer. A physical channel mapping section 111 maps the TrCH data of the bit number with the data on the physical channel.