1. A masquerading detection system comprising: an imaging unit obtaining a first image by imaging an inspection object from a first angle, and a second image by imaging the inspection object from a second angle which is different from the first angle; a feature point coordinate calculating unit detecting first feature points from the first image, obtaining first feature point coordinates representing positions of the detected feature points, detecting second feature points from the second image, and obtaining second feature point coordinates representing positions of the detected feature points; a feature point associating unit associating the first feature points with the second feature points; a feature transforming unit obtaining transformed coordinates by performing a plane projective transformation for the second feature point coordinates from the second image to the first image; and a similarity determining unit determining that masquerading has been attempted when a difference between the transformed coordinates and the first feature point coordinates is equal to or smaller than a predetermined value.