1. An image recognition information attaching apparatus comprising: a retrieving unit that retrieves image information on a per piece basis of identification information, from the image information having the identification information associated thereto in advance; a generator unit that generates feature information from the image information retrieved by the retrieving unit; and a learning unit that provides a learning result by learning a relation between the feature information generated by the generator unit and the identification information of the image information corresponding to the feature information, using a stochastic model including a mixture of a plurality of probability distributions, the learning unit calculating, from a first variable determined from the feature information belonging to one of the probability distributions, and a variable describing a probability distribution determined from a set of the feature information resulting from all the image information retrieved by the retrieving unit regardless of the content of the identification information, a second variable in accordance with a contribution ratio responsive to a density of the feature information belonging to the one of probability distributions, and learning the relation using a distribution described by the second variable.