Abstract: A throughput measuring method includes: acquiring a plurality of data packets at an observation point on a network, the plurality of data packets being transmitted from a transmission source apparatus and received by a transmission destination apparatus; calculating a plurality of round trip times, for each of the data packets, from a time point of acquisition of each of the data packets transmitted from the transmission source apparatus to a time point of acquisition of response packet corresponding to each of the data packets; identifying a measurement time section including the plurality of calculated round trip times increasing in ascending order of identification numbers of the response packets; and calculating a throughput of the identified measurement time section based on data quantities of the plurality of data packets transmitted from the transmission source apparatus during the identified measurement time section.