An operation management apparatus obtains a value Xi indicating the number of process requests being processed by an information processing apparatus during each sampling operation, from N samplings acquired during a specific time period from the information processing apparatus, wherein N is an integer satisfying a condition of 1≦N, and i is an integer satisfying a condition of 1≦i≦N. The apparatus determines, for a plurality of information processing apparatuses, a ratio of the sum of values Xi, each value Xi having a difference, from a maximum value of the values Xi, falling within a specific range, to the total sum of the values Xi. The apparatus detects an information processing apparatus having the ratio equal to or higher than a specific value.