To provide a node connection method capable of asynchronously inserting and deleting a node, while keeping consistency in connection relation in a distribution system where the multiple nodes are connected via a network.

When a third node is to be inserted between a first node and a second node being the connection destination of the first node, the third node acquires detection information which is held by the first node and updated when the connection destination of the node is changed, and subsequently transmits to the first node a link update message including the detection information and connection destination information for connecting to the third node. The first node determines whether or not the detection information held by the first node when the link update message is received coincides with the detection information included in the link update message. When the coincidence is determined, the first node is connected to the third node based on the connection destination information, and also the detection information held by the first node is updated to different detection information.