1. A fingerprint input device comprising: a two-dimensional image sensor for picking up a fingerprint image from a fingerprint measured portion of a measurement target finger, said fingerprint measured portion having a fingerprint ridgeline portion and a fingerprint valley portion; and a transparent solid film mounted on an image pickup surface of said two-dimensional image sensor, said fingerprint measured portion being mounted on said transparent solid film when said two-dimensional image sensor picks up said fingerprint image, wherein said fingerprint input device picks up an image of said fingerprint ridgeline portion in said fingerprint measured portion as a light portion, and picks up an image of said fingerprint valley portion in said fingerprint measured portion as a dark portion, and wherein a refractive index of said transparent solid film is 1.4 or more.