The present invention is a cross-connect protection method that protects a cross-connect in a system where a plurality of network management terminals monitor a plurality of network elements constituting a network and the cross-connect at each of the network elements is controlled. An arbitrary one of the network management terminals instructs locking and unlocking of a cross-connect set in an arbitrary one of the network elements. The arbitrary network element controls the instructed locking and unlocking of the set cross-connect. Hence, when conducting a test, after locking a cross-connect set in an actual operation, a cross-connect of a testing network element is set/canceled for the test. Accordingly, it is possible to avoid erroneous cutting off of a signal used in the actual operation.