A brain disease diagnosis assistance system acquires a plurality of learning data items, each including brain wave feature data including feature amounts of brain waves extracted from the brain waves and disease information attached to the brain wave feature data, the disease information indicating a state of a brain disease corresponding to the brain wave feature data and classifies the plurality of acquired learning data into a plurality of clusters. A classifier for classifying learning data into portions corresponding respectively to types of disease information is generated based on disease information attached to learning data in each classified cluster. Then, brain wave feature data of a subject is acquired and a cluster to which the brain wave feature data is classified is specified and one of a plurality of brain diseases, which corresponds to the brain wave feature data of the subject, is determined through the generated classifier.