Provided is a pipe network evaluation device that is capable of calculating a pressure loss in a pipe network and a consumption flow rate of compressed air in each terminal equipment without inputting layout information on devices, even in a case where there are some devices, the layout information about which is difficult to ascertain visually or obtain from a building drawing, or the like. Provided is a pipe network evaluation device that estimates the resistance of a pipe, the layout information about which is unknown, on the basis of pressure data on compressed air in an air tank, flow rate data on compressed air supplied from the air tank, layout unknown-part pipe outlet pressure data, for which layout information is unknown, and layout known-part pipe layout information, for which layout information is known.