A partial image is cut out from an input image. A first classifier judges whether the partial image includes a face facing a direction within a first angular range. Another classifier judges whether the partial image includes a face facing a direction within another angular range that partially overlaps with the first angular range. The partial image is judged to include a face facing a direction within a specific angular range, which is the first angular range from which the portion that overlaps with the other angular range has been removed, if the first classifier judges that the image includes a face facing a direction within the first angular range, and the other classifier judges that the image does not include a face facing the second angular range. Each classifier is generated by machine learning, and judges whether images include faces facing directions corresponding to predetermined angular ranges.