A packet processing apparatus includes a packet processing engine and a search engine connected through a bus having a bandwidth which is equal to or greater than a total transmission bandwidth of one or more receiving ports. The packet processing engine is configured to append a device internal header containing a search key to each of the packets, transfer the packets to the search engine through the bus, and receive the packets whose device internal headers are provided with search result information from the search engine through the bus. The search engine includes a packet buffer for temporarily storing the packets, a search processing part for performing search processing on the basis of the search key in the device internal header, and means for transferring the search result information from the search processing part and the packets stored in the packet buffer to the packet processing engine.