1. An image retrieval device, comprising: image input means for inputting an image; search target image storing means for respectively storing a plurality of search target images to be searched; search target image extracting means for comparing an input image feature amount that is based on an attribute of an input image that is input by the image input means with search target image feature amounts, each of the search target feature amounts being based on an attribute of each of the search target images, and extracting an extracted search target image that is similar to the input image from the search target images stored in the search target image storing means; and search result output means for outputting the extracted search target image as a search result, each of the search target image feature amounts comprises: a first feature amount calculated about each of a plurality of pixels extracted from pixels constituting each of the images in accordance with a predetermined condition by counting the number of other pixels existing radially from a focused pixel in each of predetermined directions and statistically processing a distribution state of the number of pixels counted in each of the predetermined directions; and a second feature amount calculated about each of the plurality of extracted pixels by statistically processing presence and absence patterns of two or less pixels adjacent to the focused pixel with respect to the focused pixel into 3 to 5 kinds of feature amount groups of the presence and absence patterns.