Provided is a communication terminal device that reduces, in a network using a power line, the percentage of bands consumed for transmission of control packets in the bands consumed for all the communication, so as to ensure transmission of data intended to be transmitted. A PLC terminal F701 connected to the network of power line communication transmits, when having determined that the terminal does not receive from the network a beacon for a predetermined period of time, a beacon request packet to the network, using a modulation method having the lowest communication speed among the modulation methods that can be used in the network.