A personal identification system comprising: a light source; an imager configured to capture an image of light transmitted through a finger; input means for receiving input from a user or an administrator; and a processor configured to perform registration of a blood vessel pattern extracted from the captured image and identification by comparing the extracted blood vessel pattern and a previously registered blood vessel pattern, wherein the processor, when performing registration of an extracted blood vessel pattern, is adapted to calculate a wrinkle level as a value indicating the overall amount and darkness of wrinkles on the finger surface in the extracted blood vessel pattern and a blood vessel level as a value indicating the overall amount and darkness of blood vessels in the extracted blood vessel pattern by distinguishing wrinkles from blood vessels via their respective line thicknesses in the extracted blood vessel pattern, wherein blood vessels correspond to thick lines and wrinkles correspond to thin lines, to evaluate suitability for identification from the wrinkle level and the blood vessel level by calculating an identification suitability result, wherein the identification suitability result varies proportionally with the blood vessel level and inversely with the wrinkle level; to present the identification suitability result to the user or the administrator in order to allow him to input through the input means a selection of whether the blood vessel pattern extracted from the captured image is to be registered; and, if the user or the administrator has selected to the registration of the blood vessel pattern extracted from the captured image, to register the blood vessel pattern. a light source; an imager configured to capture an image of light transmitted through a finger; input means for receiving input from a user or an administrator; and a processor configured to perform registration of a blood vessel pattern extracted from the captured image and identification by comparing the extracted blood vessel pattern and a previously registered blood vessel pattern, wherein the processor, when performing registration of an extracted blood vessel pattern, is adapted to calculate a wrinkle level as a value indicating the overall amount and darkness of wrinkles on the finger surface in the extracted blood vessel pattern and a blood vessel level as a value indicating the overall amount and darkness of blood vessels in the extracted blood vessel pattern by distinguishing wrinkles from blood vessels via their respective line thicknesses in the extracted blood vessel pattern, wherein blood vessels correspond to thick lines and wrinkles correspond to thin lines, to evaluate suitability for identification from the wrinkle level and the blood vessel level by calculating an identification suitability result, wherein the identification suitability result varies proportionally with the blood vessel level and inversely with the wrinkle level; to present the identification suitability result to the user or the administrator in order to allow him to input through the input means a selection of whether the blood vessel pattern extracted from the captured image is to be registered; and, if the user or the administrator has selected to the registration of the blood vessel pattern extracted from the captured image, to register the blood vessel pattern. to calculate a wrinkle level as a value indicating the overall amount and darkness of wrinkles on the finger surface in the extracted blood vessel pattern and a blood vessel level as a value indicating the overall amount and darkness of blood vessels in the extracted blood vessel pattern by distinguishing wrinkles from blood vessels via their respective line thicknesses in the extracted blood vessel pattern, wherein blood vessels correspond to thick lines and wrinkles correspond to thin lines, to evaluate suitability for identification from the wrinkle level and the blood vessel level by calculating an identification suitability result, wherein the identification suitability result varies proportionally with the blood vessel level and inversely with the wrinkle level; to present the identification suitability result to the user or the administrator in order to allow him to input through the input means a selection of whether the blood vessel pattern extracted from the captured image is to be registered; and, if the user or the administrator has selected to the registration of the blood vessel pattern extracted from the captured image, to register the blood vessel pattern.