Abstract: In an open environment, a consensus building means for maintaining dependability throughout the entire life cycle of a target system between stakeholders is provided, thereby appropriately operating the target system in accordance with the content of an agreement between the stakeholders. A consensus building support tool provides a support for consensus building through an argument regarding an ordinary operation state of a target system. History obtained in the process of the consensus building is recorded in a database layer as an agreement graph. A monitoring node tool detects deviation from the ordinary operation state of the target system based on an actual operation state of the target system and the agreement graph. A contract generating tool extracts information data regarding the consensus building from the agreement graph when the deviation from the ordinary operation state is detected in the target system.