A terminal count acquisition unit (1001) acquires the number of terminal apparatuses included in an air-conditioning system (500) and the number of terminal apparatuses connected to a data relay apparatus (100). Using the number of terminal apparatuses included in the air-conditioning system (500) and the number of terminal apparatuses connected to the data relay apparatus (100), the numbers of the terminal apparatuses having been acquired by the terminal count acquisition unit (1001), a transmission rate calculation unit (1002) calculates a transmission rate to be set in the data relay apparatus (100). A transmission rate setting unit (1003) sets, in the data relay apparatus (100), the transmission rate calculated by the transmission rate calculation unit (1002).
