A communication device for transmitting and receiving data to and from a communication terminal device (11a, 11b, 11c) by transmitting a signal for establishing transmission and reception of the data to the communication terminal device when the communication terminal device, which alternately switches between an active state and a sleep state, is in the active state, the active state being a state in which communication is possible, and the sleep state being a state in which communication is not possible, the communication device comprising: a power saving control unit configured to determine a transmission period in such a manner that the transmission period during which the signal is transmitted is increased; and a first communication interface unit configured to transmit the signal containing information indicating the determined transmission period to the communication terminal device so as to set the communication terminal device in the active state with a period according to the determined transmission period, characterized in that the power saving control unit is configured to determine the transmission period in such a manner that the transmission period during which the signal is transmitted is increased as a power value difference increases which is a value obtained by subtracting a total power consumption value of the power consumption appliance from the available power supply value, and in that the communication device further comprises: a second communication interface unit configured to (i) communicate with a distribution board that measures a total power consumption value of a power consumption appliance including the communication terminal device and (ii) receive information indicating the total power consumption value from the distribution board; a storage unit configured to store the total power consumption value received from the distribution board and an available power supply value indicating a power value available to be supplied to the power consumption appliance. a power saving control unit configured to determine a transmission period in such a manner that the transmission period during which the signal is transmitted is increased; and a first communication interface unit configured to transmit the signal containing information indicating the determined transmission period to the communication terminal device so as to set the communication terminal device in the active state with a period according to the determined transmission period, characterized in that the power saving control unit is configured to determine the transmission period in such a manner that the transmission period during which the signal is transmitted is increased as a power value difference increases which is a value obtained by subtracting a total power consumption value of the power consumption appliance from the available power supply value, and in that the communication device further comprises: a second communication interface unit configured to (i) communicate with a distribution board that measures a total power consumption value of a power consumption appliance including the communication terminal device and (ii) receive information indicating the total power consumption value from the distribution board; a storage unit configured to store the total power consumption value received from the distribution board and an available power supply value indicating a power value available to be supplied to the power consumption appliance. a second communication interface unit configured to (i) communicate with a distribution board that measures a total power consumption value of a power consumption appliance including the communication terminal device and (ii) receive information indicating the total power consumption value from the distribution board; a storage unit configured to store the total power consumption value received from the distribution board and an available power supply value indicating a power value available to be supplied to the power consumption appliance.