A computer analyzes the root cause of an event, which has occurred in any of multiple management-target apparatuses, based on one or more rules in a storage device, that denote an association between one or more condition events corresponding to one or more events capable of occurring in any of the multiple management-target apparatuses and a conclusion event, which is the cause in a case where the one or more condition events have occurred. The computer, based on an event occurrence log including contents and an occurrence date and time of an event, determines a first event group, which is multiple events presumed to occur as a result of the same cause, creates a new rule in which the multiple events of the first event group are the condition events and one event of the first event group is the conclusion event, and stores the created new rule.