1. A character noise eliminating apparatus for eliminating a character noise which is an atypical shaped background noise from a fingerprint or a palm print image, the apparatus comprising: a character noise area determining device for repeating a processing, in which a binary image is generated by binarizing the image with a binarization threshold inputted by an operator and the binary image is displayed on a data display device, until the operator indicates confirmation that a character noise area is detected properly, and determining the character noise area depending on a binary image finally generated; a density conversion area layer determining device for setting a plurality of density conversion area layers inside and outside the character noise area; and a density converting device for, as a reference area of a target pixel, setting a neighboring pixel group within the same density conversion area layer as the density conversion area layer to which the target pixel belongs, and generating a density converted image by applying local image enhancement.