1. A character segmentation section, for segmenting characters of a character line, for use in a character segmentation device which processes multi-level image data acquired by imaging said character line, in which a linear drawing is present, on an information recording medium said character segmentation section comprising: a minimum pixel-value curve creating section configured to extract a smallest pixel value in pixels composing a pixel line arranged in a direction orthogonal to a character line direction in said multi-level image data and create a minimum pixel-value curve, a character partitioning position determining section configured to determine partitioning positions of said characters, based on said minimum pixel value curve, a binarization processing section configured to detect a minimum pixel value indicating said linear drawing from said minimum pixel-value curve, acquires a binarization threshold based on said minimum pixel value, and binarizes said multi-level image data using said binarization threshold, and a character segmentation implementing section configured to extract the image data of each character.