Within a finger vein authentication input apparatus, a finger positioning portion comprises a fingertip projection portion provided at a position corresponding to the tip of the finger when picking up an image thereof, protruding into the horizontal direction, soas to be in contact with a tip of a finger, horizontally, a finger pulp projection portion provided at the position corresponding to the tip of the finger when picking up the image thereof, protruding into the vertical direction, so as to be in contact with the tip of the finger, vertically, and a base guide portion provided at the position corresponding to the base side than a second joint of the finger when picking up the image thereof, having a configuration curved along the cross-section configuration of the finger, or a curved configuration including a projection portion at a center thereof, thereby increasing an accuracy of positioning the finger in the longitudinal direction thereof, and further lowering shift of angle of attaching the finger in the longitudinal direction thereof.