Node device, a network participation processing program, and a network entry process method such as

To provide a node device, a network participation processing program, and a network participation processing method which enables to configure an overlay network in which consideration has been given to locality and to reduce unnecessary load to an actual network. The present invention is a node device which participates in an overlay network formed by participation of all or part of a plurality of node devices which are connected with each other via communication means, which includes search information transmission means for transmitting search information for searching a node device to which participation request information indicating participation request to the overlay network is to be transmitted to an information processing device connected to the communication means, reply information receiving means which is a plurality of node devices participating in the overlay network and receives reply information replied from the plurality of node devices which have received the search information transferred by the information processing device respectively, communication load information obtaining means for obtaining information regarding communication load in a communication route between the node device that replied each of the reply information and the node device itself, communication load comparison means for comparing information regarding communication load in each of the communication routes, node device selection means for selecting a node device to which the participation request information is to be transmitted among the plurality of node devices, which have replied the reply information, on the basis of comparison result by the communication load comparison means, and participation request information transmission means to transmit the participation request information to the selected node device.