A network failure detecting method for detecting a failure of a network including a number of transferring devices by tracing data flow rates of the transferring devices based on physical topologies of the transferring devices for the network, composing a group of the transferring devices adjacent to one another, data flow rates of which have failed to be obtained, as one virtual transferring device; and replacing physical topologies of the group of the transferring devices adjacent to one another, data flow rates of which have failed to be obtained, with a physical topology of the composed virtual transferring device.