A network control device includes first and second interfaces, a first memory, a packet converter, a first data transfer section, a filter, and a packet transmission controller. The converter converts a second type of packets of a second system in the memory into a first type of packets of a first system. The filter extracts a valid first type of packets from the first type of packets read from the memory by the transfer section. In an energy saving state, the controller generates and transmits a first type of packets for transmission of the first system to the first interface when the extracted valid first type of packets are of the first type of packets, and generates and transmits a second type of packets for transmission of the second system to the second interface when the extracted valid first type of packets are of the second type of packets.