A receiver receives data transmitted from a transmitter. The data is stored in a buffer, and a reliability value of the data is computed by a computing unit. A determining unit determines reliability of the data by comparing a reliability value of existing data in the buffer and a reliability value of the data. When the reliability value of the data is higher than a predetermined value, the existing data is combined with the data. Then, an error correcting unit performs error correcting on combined data obtained, and outputs decoded bits. If the combined data includes many errors, retransmission of the data is requested to the transmitter. When the reliability value of the data is lower than the predetermined value, retransmission of data is directly requested without combining the data with the existing data.