A storage resource stores a plugin information package, which is an information package comprising definition information for plugging in a node device as a management target. The definition information is information denoting at the least one of a method for acquiring information from a node device and an item of information to be acquired from a node device. A processor references the plugin information package, which is stored in the storage resource, and accesses a node device via a communication interface device based on the referenced plugin information package. The node device comprising information that has been correctly acquired in accordance with this access is regarded as the management target.