To improve the accuracy of fingerprint authentication, the foreign object determination device of the present invention includes an image acquisition unit 31 for acquiring an image in which an authentication target to be subjected to fingerprint authentication has been captured, a region partitioning unit 33 for partitioning the image acquired by the image acquisition unit 31 into regions of mutually different colors by using predetermined determination criteria for determining differences in color, and a foreign object determination unit 34 for determining whether a foreign object is included in the authentication target by using colors and/or areas of the regions partitioned by the region partitioning unit 33.
