The quality control system includes a network, a plurality of medical diagnostic apparatuses which exist on the network and have respective histories of evaluation results on specific items regarding quality of individual medical diagnostic apparatuses and a control device which exists on the network, stores all of the histories of the evaluation results that individual medical diagnostic apparatuses hold and controls them centrally. By this unified quality control system, quality control of a plurality of medical diagnostic apparatuses connected to each other on the network can efficiently be performed.