1. A personal identification device comprising: a storage for storing vein patterns of registered finger images, an interface provided with a light source and a camera for receiving light transmitted through fingers, and means for extracting a vein pattern contained in the received image of light transmitted through the fingers and identifying a person by collating the extracted vein pattern with the vein patterns of registered finger images, wherein: said interface has a slot into which fingers are inserted, and said light source and said camera are arranged opposite each other with the slot between them.