A data acquisition means acquires source domain data and target domain data. An alignment means performs an alignment which converts the source domain data and the target domain data into images of a predetermined reference angle. A feature extraction means extracts local features of the source domain data and the target domain data. A classification means classifies a class based on the local features of the source domain data and the target domain data after the alignment. A learning means trains the feature extraction means based on the local features of the source domain data and the target domain data after the alignment and a classification result of the class.