When searching for a starting point candidate on an abnormality occurred in a first management range, if a search destination extends over a second management range, a first search device transmits a query to a second search device and requests a second search device to search for a starting point of an abnormality in the second management range. The second search device receives the query, searches the second management range for a starting point candidate of an abnormality, replaces a starting point candidate of an abnormality with a dummy configuration item, and transmits a response. Thus, the first search device can search for a starting point candidate of an abnormality without grasping a connection relationship of configuration items in the second management range.