Address information of a mail to be transmitted by a mail communication function is extracted from the mail to be transmitted; a transmission time of the mail to be transmitted is extracted from a portable information terminal; and judgment is made as to whether the address information matches predetermined address information and whether the transmission time belongs to a predetermined time zone. When the address information matches the predetermined address information, and the address information belongs to the predetermined time zone, an activation time at which a household appliance is to be activated is determined on the basis of the transmission time, and a control command for activating the household appliance at the activation time is transmitted to a network.