To examine the feasibility of estimating the degree of “strength of belief (SOB)” of viewer’s responses using support vector machines (SVM) trained with features of gazes, the gazing features were analyzed while subjects reviewed their own responses to multiple choice tasks. Subjects freely reported the certainty of their chosen answers, and these responses were then classified as high and low SOBs. All gazing points of eye-movements were classified into visual areas, or cells, which corresponded with the positions of answers so that training data, consisting of the features and SOB, was produced. A discrimination model for SOB was trained with several combinations of features to see whether performance of a significant level could be obtained. As a result, a trained model with 3 features, which consists of interval time, vertical difference and length between gazes, can provide significant discrimination performance for SOB.