A network relay node device for relaying communication between a first network and a second network having a protocol different from a protocol of the first network through a switch, the network relay node device includes an identical segment information generation control unit that generates identical segment information for identification of another relay node device belonging to a same segment as a local device in the second network and a loop suppression control unit that suppresses a loop of a communication including the switch by broadcasting a received broadcast frame only to a connection port of the first network if the identical segment information is detected in identification source node information acquired from a header of the broadcast frame when the broadcast frame is received from a connection port of the first network.