1. A biometric image output control method for a biometric authentication device including a living body imaging unit, the method comprising: generating a biometric image by imaging a living body to be authenticated; determining whether an imaging environment for the living body to be authenticated satisfies a predetermined recognition condition; when the imaging environment satisfies the predetermined recognition condition, controlling a change rate of a size of the biometric image, a change rate of a focal point of the biometric image, and a change rate of brightness of the biometric image according to a change of a distance from the living body imaging unit to the living body to be authenticated; and when the imaging environment does not satisfy the predetermined recognition condition, controlling at least one of the change rate of the size of the biometric image, the change rate of the focal point of the biometric image, and the change rate of the brightness of the biometric image to be greater than the change of the distance from the living body imaging unit to the living body to be authenticated.