7. An event analysis method by a management computer which includes storage resources and manages a plurality of computers to be managed, the method comprising: storing, in the storage resources: (1) topologies indicating relationships among a plurality of managed objects, which are the plurality of managed computers or a plurality of components included in the plurality of managed computers; (2) event propagation models, each including a set of information on one or more events and a causal event to cause the one or more events defined with types of events and types of managed objects where events occur, one of the event propagation models indicating that events of type A which occur to managed objects of type 1 cause events of type B to occur to management objects of type 2; and (3) causality information including one or more causal relations, one of the causal relations indicating that a first event of type A which occurs to a first managed object of type 1 causes a second event of type B to occur to a second managed object of type 2; (A) detecting an event relating to a problem that has occurred to a managed object; (B) determining whether a first causal relation to be used in analysis of the detected event has been created in the causality information; (C) performing, in a case where the processor determines that the first causal relation has not been created in (B), an on-demand expansion based on one of the topologies and one of the event propagation models to create the first causal relation in the causality information; performing, in a case where the processor determines that the first causal relation is being created in (B), an on-demand expansion based on one of the topologies and one of the event propagation models to create the first causal relation in the causality information; and (D) analyzing the detected event using the first causal relation.
11. An event analysis method according to claim 7 , further comprising (H) suspending on-demand expansion of other causal relations having the same cause as a causal event indicated by the first causal relation during the on-demand expansion relating to the first causal relation.