A transmission-time measurement section (201) and a jitter measurement section (202) measure transmission time length and jitter, respectively, by using the packets transmitted/received. A forward-error-correction (FEC)-scheme maximum-jitter measurement section (203) calculates a maximum jitter in the case of adopting an FEC scheme, and an automatic-retransmission-request (ARQ)-scheme maximum-jitter measurement section (204) calculates a maximum jitter in the case of adopting an ARQ scheme from the measured information. A packet control section (205) selects a communication scheme having a smaller maximum jitter from both schemes based on the calculation result of the FEC-maximum-jitter measurement section (203) and ARQ-maximum-jitter measurement section (204).