Face authentication can easily be performed based on an input image including a mirror region reflected by a mirror without increasing a storage capacity of a database. With the database, for each face of a person to be authenticated, only one real front image is to be registered as a reference face image. A mirror image processing circuitry detects the mirror region from the input image and to subject a detected mirror region to lateral inversion processing to produce a processed image. A face detection processing circuitry detects a face image from the processed image to generate a detected face image. A face authentication processing circuitry compares the detected face image with the reference face image, to thereby perform face authentication.