Abstract: The network monitoring system includes: a monitoring equipment 10; and a reproduction terminal 20 which decompresses compressed image data included in monitoring information transmitted by the monitoring equipment through a network line 40; a calculation unit for calculating the transmittable amount of information 501 which calculates the transmittable amount of information per unit time of the network line; and a calculation unit for calculating the transmitted amount of information 502 which calculates the transmitted amount of information per unit time of the monitoring information to be transmitted on the basis of a predetermined occupation ratio in order to determine a ratio of the monitoring information to the calculated transmittable amount of information, and the amount of information per unit time of monitoring information to be transmitted from the monitoring equipment is controlled on the basis of the transmitted amount of information per unit time that has been calculated by the calculation unit f