1. A device to extract a biometric feature vector comprising: a memory device configured to store an enrolled biometric feature vector in advance; and a circuitry, wherein the circuitry is configured: to obtain a biometric image; to generate a plurality of small region images from the biometric image so that variability of biometric information amounts among the plurality of small region images is equal to or less than a predetermined value; to extract biometric local feature amounts from the small region images; to generate a biometric feature vector by combining the biometric local feature amounts in accordance with a predetermined rule, the biometric feature vector indicating a feature for identifying the biometric image, the biometric local feature amounts being arranged in a predetermined order in the biometric feature vector; and to perform comparing of the biometric feature vector with the enrolled biometric feature vector by a distance calculation and determine whether a user is genuine.