The independencies of a plurality of layers executing dividingly a transaction can be easily enhanced. Anode (30) assigns to a transaction to anode (30) of a lower layer through a distributed transaction management section. The node (30) shares a predetermined transaction with the node (30) of the lower layer along with other nodes (30). The node (30) shared by the nodes (30) is a read-only node or a node to which data can be written by the characteristic of a function. Thus the node (30) searches for an unused node (30) in lower layers through the distributed transaction management section (34) when the node starts a new transaction. First, second, and third node hosts (3,4,5) check if each node (30) is used for which transaction or if each node (30) is used or not and store the results.