An image matching device includes a section calculates feature points on an input document image, a section that calculates features of the input document image in accordance with a relative position between the calculated feature points, and sections for comparing the calculated features of the input document image with features of a reference document image to determine whether the input document image is similar to the reference document image. When it is determined that the input and reference documents are similar, a document discrimination section determines a position of an image on the input document and similar to the reference document image, in accordance with the positions of the coordinates of the feature points on the input document and on the reference document.