1. A character recognition method for recognizing a character printed over a background pattern on a valuable medium, comprising: capturing an image of the valuable medium; cutting out an image of a partial area from the image of the valuable medium; acquiring a character image from the image of the partial area, the character image including the character that is to be recognized, which is printed on the valuable medium; evaluating a degree of similarity between the character image and each one of a plurality of template images; and determining that the character corresponding to a template image showing the highest degree of similarity at the evaluating is the character included in the character image, wherein the template images have been previously prepared for all characters that the valuable medium is likely to include, and in each of the template images, a background area separated from a character is filled with a single pixel value that is determined in accordance with characteristics of the background area.