1. A face authentication system, comprising: a data processing section for performing a predetermined data processing operation; a first data input section for inputting three-dimensional data on a face area of a subject to the data processing section; and a second data input section for inputting two-dimensional image data on the face area of the subject to the data processing section, the two-dimensional image data corresponding to the three-dimensional data to be inputted to the data processing section, wherein the data processing section includes: a quality rating section for rating the quality of the three-dimensional data with respect to the two-dimensional image data based on a state of subject and/or a state of image capturing while acquiring the three-dimensional data, and generating quality data, and an authentication processing section for executing a registration process or a verification process of authentication data based on the three-dimensional data, if the quality data satisfies a predetermined requirement.