According to the present invention, a backlight infrared image sensor comprises: a bulk silicon layer formed with bulk silicon; an epi-silicon layer which is formed with epitaxial silicon including a plurality of photo diodes on the lower surface of the bulk silicon layer; and a wiring formation layer configured to form oxide and metal layers on the lower surface of the epi-silicon layer, wherein the thickness (tbulk) of the bulk silicon layer is adjusted to pass light in a specific band.