A technology that increases bill discrimination precision, wherein a bill discriminating apparatus detects the thickness distribution of a bill P that is subject to discrimination, and by comparing this thickness distribution data and the reference thickness distribution data that shows the thickness distribution of an authentic note held in advance, performs discrimination processing that includes double feed detection, tape detection, and authenticity discrimination. Then, authenticity discrimination is performed on areas for which the difference between the thickness distribution data and the reference thickness data is within a specified range.