The invention aims to provide an image retrieving device which can highly increase processing speed involved in retrieving processing and improve retrieving precision of document and image data. In the step A1, a front processing part (130) performs binarization processing which is taken as preprocessing for the input image data; in the step A2, based on the binarized image data, a characteristic extracting part (131) extracts the characteristic quantity of the binarized image data; in the step A3, a retrieving part (132) compares the characteristic quantity of registered image data with the characteristic quantity of the binarized image data, and retrieves the image data which has high similarity to the input image data from the registered image data; and in the step A4, a retrieving result is output to a display part (14), wherein the characteristic quantity is an array which is formed by arranging a word length ratio fn of each two adjacent words according to the arrangement sequence of the words.