To set the priority of a packet belonging to a data flow in response to the domain name of the transmission device of the data flow.

Provided is an HGW 101 including: a QoS object storage unit 22 which acquires a communication address corresponding to a domain name included in a request to request the IP address of a video distribution server 603, and stores it by associating the domain name of the video distribution server 603 with priority to be set in a communication packet to be transmitted from the video distribution server 603; a priority data generation processing unit 13 which acquires the priority to be associated with the domain name included in the request from the QoS object storage unit 22, associates the acquired priority to the group of the domain name included in the request and the acquired communication address, and stores the priority and the group in a packet priority storage unit 23; and a packet priority modification process unit 14 which acquires the priority to be associated with the group of the communication address of a transmission source of the communication packet and the communication address of a transmission destination from the packet priority storage unit 23, and sets the priority in the communication packet.