An image monitoring system that efficiently utilizes a network band and decrease the processing load of a server is provided. A second image decision processor analyzes an extracted image transmitted from a monitoring terminal, and evaluates the quality (reliability) of the extracted image. A reliability decision unit outputs an individual ID of the analyzed extracted image to a load estimation unit when the numerical value from the analysis output by the second decision processor becomes less than the preset threshold. The load estimation unit estimates the server processor load of a server and the network load. A resend request unit controls the resend request for an individual ID output from the negative load estimation unit corresponding to the server processor load and the network load.