A network relay device capable of easily recognizing a state of hash value collision is provided. Each of a plurality of entries contained in an address table includes: a first area in which first information is registered, the first information indicating a relation between a plurality of ports and MAC addresses existing beyond the plurality of ports; and a second area in which second information is registered. In learning a transmission-source MAC address of a frame received at a port, a frame processing unit calculates a hash value by using the transmission-source MAC address first. Next, if a MAC address different from the transmission-source MAC address has been registered in the first area of an entry corresponding to the hash value, the frame processing unit registers the second information in the second area.