To provide a high speed packet filter mechanism capable of complicated processing in small circuit scale.

Concerning a packet filter for sorting out packets on conditions such as specified address or specified protocol, this filter is provided with a memory 104 for preserving filtering conditions while dividing them into plural pieces, a comparative discriminating function part 120 composed of hardware for reading these divided filtering conditions out of the said memory and discriminating them comparatively with one part of respectively correspondent packets and a compared result coupling part 110 composed of hardware for coupling these discriminated result through OR or AND and determining sorting of packets on the basis of this result.