1. A method of receiving a signal generated by modulating, according to a modulation procedure, a data string coded with an error correction code and interleaved for each packet as a transmission unit so that one symbol represents one of a bit and a plurality of bits, the method comprising: demodulating the received signal and generating a soft-decision value used for decoding the error correction code; de-interleaving the soft-decision value; decoding the error correction code using the de-interleaved soft-decision value; calculating an evaluation value for evaluating a reception level of the received signal detected more than once during a predetermined measurement time based on the reception level; and correcting the soft-decision value generated at the demodulating so as to decrease a contribution to the decoding of the error correction code when the evaluation value indicates the occurrence of interference, wherein the soft-decision value is interleaved across a plurality of symbol periods with different timings, and the de-interleaving de-interleaves the soft-decision value across the plurality of symbol periods.