A packet communication apparatus that carries out packet communication with a second packet communication apparatus via a logical connection through header processing of compressing or decompressing a packet header, the apparatus managing a first state machine of a first header processing state concerning a first packet flow of the connection and a second state machine of a second header processing state concerning a second packet flow of the connection; and controlling a state transition of a third state machine that is one of the first state machine and the second state machine on the basis of a state transition of a fourth state machine that is the other of the first state machine and the second state machine.