1. A moving amount detection method, comprising: continuously inputting living body section images of a human body part by relative movement with respect to a read unit, a biometric portion image of a human body part read in sequentially, in an order of when sections of the human body part contact the read unit, containing a common region agreeing with the image read immediately therebefore; extracting character shapes from the living body section images; and searching common areas in which the character shapes match from two living body section images which are chronologically continuous to detect relative amounts of movement of the images.