To provide the method and the network system for detecting and eliminating infinite relaying of packets by which a spanning tree protocol STP is always in normal operation so that no storm occurs in the network.

In the method for detecting and eliminating infinite relaying of packets using a network system 1-1 having a plurality of (2 or over) ports 2-1, 2-2, 2-3 such as a switching hub or a bridge that has a function of relaying data among information communication devices connecting with the ports 2-1, 2-2, 2-3, a sender address in a packet received by the ports 2-1, 2-2, 2-3 is monitored. When the packet having the same sender address has been received by the plurality of the ports 2-1, 2-2, 2-3 within a prescribed time, relaying of packets other than a bridge protocol data unit BPD is stopped.