A receiver performs independent packet detection using synchronization words with orthogonality when multiple signals on which frequency-shift keying is performed coexist. The receiver includes a frequency demodulator generating a quasi-amplitude modulation signal that has a value proportional to frequency shift from the first signal or second signal being received, a sign discriminator discriminating a sign of the generated quasi-amplitude modulation signal, and a multi-binary correlator calculating a first correlation value which is a binary correlation value between the discriminated sign and a first synchronization word and calculating a second correlation value which is a binary correlation value between the discriminated sign and a second synchronization word.