In a forwarding device connected to a network including a plurality of communication nodes connected to each other, in which a plurality of communication routes, each for forwarding a signal through at least one of the communication nodes can be present between arbitrary ones of the communication nodes, a forwarding method according to the present invention determines that the received packet is a BPDU or a local BPDU, and discards the BPDU if the received packet is the BPDU and fetches an original BPDU from the local BPDU if it is the local BPDU. In the case where the BPDU is to be transmitted, the BPDU is created and wrapped in a format of the local BPDU. Then, the wrapped BPDU is broadcasted. In this manner, the local BPDU can be exchanged without affecting the other bridges having a normal spanning tree function.