When measuring a one-way packet transfer delay between first and second measurement devices in a time-asynchronous manner, the first measurement device transmits first packets each containing a first counter value at a time of transmission; and then transmits a second packet containing a second counter value at the time of the transmission. The second measurement device stores the first counter value extracted from each of the first packets, a third counter value at a time of reception, and reception time stamp information; calculates an incremental ratio between the first counter value and the third counter value per unit time; and calculates an expected fourth counter value at the time of the reception based on the second counter value and the incremental ratio, and obtains the transfer delay based on the calculated expected fourth counter value and an actual fourth counter value at the time of the reception.