The objective is to achieve highly accurate authentication even when there is variation in the ambient light environment during biometric imaging. A biometric authentication device includes an image capturing unit that captures images of a living body, a light source for capturing images of the living body, an optical filter that selectively passes and blocks light according to wavelength, a spectroscopic processing unit that separates multiple wavelengths captured simultaneously, respectively, and a calculation unit that calculates the shape and posture of a predetermined part of the living body in the captured images, a background removal unit that removes the background from the image of the living body using the spectral images of the living body and the spectral image of the unwanted ambient light, and an authentication unit that performs biometric authentication using the image of the predetermined part.