An image retrieving apparatus that can suitably retrieve a similar image of image data whose density has changed. Image data is inputted from image input unit 12. Image feature amount extraction unit 14 divides normalized image data to plural regions, and extracts a feature amount in units of region. Feature amount label matrixing unit 15 generates a feature amount matrix. The feature amount matrix and image data are stored in image management DB 18 in association with each other. When query image data is designated, pattern matching unit 16 determines a similarity level between a feature amount matrix of the query image data and the feature amount matrix of the image data stored in the image management DB 18.