A transmitting/receiving apparatus includes a packet construction section for dividing continuous data into a plurality of subpackets, and constructing a packet by concatenating the plurality of subpackets; a modulation transmission section for modulating the constructed packet, and transmitting the modulated packet to another apparatus; a training session execution section for checking channel conditions, when a predetermined condition is satisfied, and changing a modulation rule; and a subpacket transmission confirmation section for confirming whether or not a subpacket included in the transmitted packet is transmitted successfully to the transmission destination apparatus. If the modulation rule is changed by the training session execution section, the packet construction section reconstructs a new packet by concatenating a subpacket, which is confirmed as an unsuccessfully-transmitted subpacket, with subpackets newly generated from the continuous data, and the modulation transmission section modulates the reconstructed new packet, and transmits the modulated packet.