1. A biometric authentication device comprising: a biometric sensor that obtains an image of a biometric authentication portion of a user without contacting; a distance sensor that obtains a distance between the biometric sensor and the biometric authentication portion; and a guidance image display unit that shows a guidance image for guiding the biometric authentication portion to a distance that is appropriate for the biometric sensor to obtain the biometric authentication portion, the guidance image changing continuously or in stages according to the distance obtained by the distance sensor.