A biometric authentication system includes: an image acquisition unit for acquiring an image of a living body; a light source with a predetermined wavelength band; an authentication information storage unit for, if light is emitted by the light source, setting a predetermined distance for a first distance to a first image acquired by the image acquisition unit in a depth direction so that quality of the first image is improved, extracting a first feature to be used to perform biometric authentication from the first image whose quality has been improved, and storing authentication information regarding the first feature; a feature extraction unit for, if light is emitted by the light source when performing authentication, setting the predetermined distance for a second distance to a second image acquired by the image acquisition unit in the depth direction so that quality of the second image is improved, and extracting a second feature for biometric authentication from the second image whose quality has been improved; and a comparison unit for comparing the authentication information regarding the first feature and authentication information regarding the second feature.