1. An attribute extraction method of extracting an attribute name and an attribute value associated with an input word inputted by a user from documents by a computer, wherein the computer: extracts a document including the input word inputted by the user from the pre-stored documents; delimits said extracted document into strings or images based upon a predetermined rule, and calculates a drawing position of each of said delimited strings or images; extracts a group of the strings or images of which said calculated drawing positions are arranged in one direction as an attribute group; calculates an attribute name score indicative of an extent to which said attribute group is an aggregation of attribute names based upon a statistical index employing the appearance number of each word in all of the attribute groups that is obtained from said delimited strings or images of said attribute group, and selects an attribute name group from said attribute group based upon said attribute name score; selects, from said extracted attribute group, the attribute group in which the strings or images identical to said delimited strings or images of said attribute name group are contained, and the drawing position of the above identical string or image is identical to that of said attribute name group; extracts an attribute name from the strings or image of which the drawing position is identical between said attribute name group and said selected attribute group; and extracts an attribute value corresponding to said extracted attribute name from the strings or images of said selected attribute group except for the string or image corresponding to said extracted attribute name.