A communication quality estimation system has: a plurality of equipments performing packet transmission on a network; and a communication quality estimation equipment. The plurality of equipments includes: a first equipment; a second equipment; and a third equipment placed downstream of the first equipment and upstream of the second equipment. The communication quality estimation equipment estimates communication quality in the third equipment by comparing a number of first packets satisfying a first sampling rule out of packets transmitted by the first equipment and a number of second packets satisfying the first sampling rule out of packets transmitted by the second equipment.