A face authentication device 1 includes a three-dimensional face information storage part 7 storing at least one three-dimensional face information, an imaging optical system 3 for forming an optical image containing a face of an authentication target, an image sensor 5 for photographing the optical image of the authentication target to obtain two-dimensional image data and image plane phase differential information of the face of the authentication target and a face authentication processing part 9 for performing a three-dimensional face authentication for the authentication target by collating the face of the authentication target with the three-dimensional face information stored in the three-dimensional face information storage part 7 based on the two-dimensional image data and the image plane phase differential information obtained by the image sensor.
