1. An image retrieval method for retrieving an image which is similar to a query image which is a search key from a group of images to be referred to which is a target for retrieval, said method comprising the steps of: dividing said query image into blocks and extracting a color layout feature quantity showing an average color of each block; extracting a dominant color feature quantity showing a dominant color from said query image using said color layout feature quantity; creating a replacement image in which each pixel of said query image is replaced by a pixel of the dominant color shown by said dominant color feature quantity; dividing said replacement image into a region of interest and a region of no interest, and extracting a region division feature quantity including the region of interest and the region of no interest and position information on their positions; extracting a shape of said region of interest and a shape of said region of no interest from said replacement image and said region division feature quantity, and outputting the shapes as a shape feature quantity; and calculating similarities from said extracted feature quantities and feature quantities of said group of images to be referred to.