A classification model optimum for realization of a defect classification request by a user is not known by the user. Then, the user sets a classification model which is not necessarily suitable and makes classification, resulting in degradation in classification performance. Therefore, the present invention automatically generates plural potential classification models and combines class likelihoods calculated from the plural classification models to classify. To combine, an index about the adequacy of each model, in other words, an index indicating a reliable level of likelihood calculated from the each potential classification model, is also calculated. Considering the calculated result, the class likelihoods calculated from the plural classification models are combined to execute classification.