A communication apparatus is provided which avoids such a situation that retrieval tables do not correspond with each other, and a broadcast is induced. When an input port or an output port determined by switch function units 121, 131 is a port belonging to a Link Aggregation group, frame identifying units 122, 132 copies a frame, outputs the frame from the output port determined by the switch function units 121, 131, and transfers the copied frame to a header editing 123 and 133. The header editing units 123, 133 generate a header inside an apparatus including a field indicating whether it is a copied frame and a field storing an input port number to attach the header to the frame, and transfer the frame from one of frame transferring units 13, 12 to another.