A log management system for analyzing and managing a log acquired in a computer is provided. The system generates log groups each formed of log records with reference to the log. The system identifies active periods, in each of which a display area is active, in the log groups, and compares a start-to-end period from a start time to an end time of a reference log group selected from the log groups with active periods of subject log groups other than the reference operation log group individually to identify one or more subject log groups having an active period included in the start-to-end period. The system individually determines whether to include the identified one or more subject log groups in the same first cluster as the reference log group, based on an active period length of each of the identified one or more subject log groups within the start-to-end period.