An apparatus comprises a worker information storage unit for storing a table including, for each of a plurality of workers engaged in work of development or operation of a system, a period in which the worker possessed one of a plurality of work attributes concerning to the work, a log storage unit for storing a work log recording, for each interaction among the workers, generation time of the interaction and the workers who participated in the interaction, and an evaluation unit for calculating from the work log and outputting relation strength, for each combination of the work attributes and the pairs of the workers, that indicates the strength of the relation between the workers composing the pair, based on number of times of the interactions within the pair that the workers performed when having the work attribute.