1. A biometric information obtaining apparatus, comprising: image obtaining means which captures a plurality of successive partial images of successive portions of biometric information; characteristic extracting means which obtains, from the individual partial image obtained by said image obtaining means, a characteristic contained in said individual partial image and a position of the characteristic; relative position information detecting means which detects relative position information of two or more of the partial images, obtained by said image obtaining means, based on the characteristic contained in a region in which said two or more partial images overlap; and correcting means which calculates the amount of distortion of the characteristic based on the relative position information detected by said relative position information detecting means and on the position of the characteristic in the individual partial image, and which corrects the position of the characteristic in the individual partial image based on the calculated distortion amount.