A transmission device (100) outputs, to a reception device (200), a stored amount of packets in a first transmission buffer (105) just before a certain packet has been written to the first transmission buffer. A first reception buffer amount read unit (206) in the reception device reads a stored amount of packets in a first reception buffer just before the certain packet has been read from the first reception buffer. A storage amount addition unit (207) adds the stored amount of packets in the first transmission buffer and the stored amount of packets in the first reception buffer, and a correction unit (208) adjusts the frequency of a variable frequency oscillator in a reception timestamp timer 209 so that the resulting added value is a constant value.