Abstract: A network management device for managing a plurality of network elements has a network element management data acquisition unit for acquiring, in stages, various management data possessed by the network elements when a session with a network element is resumed and when the network management device itself is started up, a rule management table for storing a dependence relationship between an operation and management data necessary to execute the operation, a feasible operation decision processing unit which, when an operation has been specified, refers to the dependence relationship to determine whether management data necessary to execute the operation has been acquired. If the necessary management data has been acquired, a network management execution unit executes network management conforming to the operation.