There is a need for providing a finger vein image inputting device that can miniaturize and thin a finger vein authentication apparatus and provide high authentication accuracy. The finger vein image inputting device according to the present invention includes a body, a band pass filter for transmitting only light of a specific wavelength, a light source for applying light to a finger placed over the band pass filter, and an imaging means for imaging transmitted light from the finger. A gradient index lens is provided between the band pass filter and the imaging means and causes refractive-index distribution around an optical axis. A polarizing filter is provided at least one of between the light source and the finger and between the finger and an imaging device.