There is provided an information retrieval apparatus which can properly retrieve information associated with a user's preference from one of a plurality of data bases having different use frequencies. An information retrieval apparatus includes: a retrieval instruction issue unit which identifies one of an information source A data base, an information source B data base and an information source C data base according to the user's operation; a retrieval keyword selection unit which preferentially selects, from a group of keywords indicating the user's preference, one or more strongly preferred keywords based on a number associated with the use frequency of the data base identified by the retrieval instruction issue unit; and a retrieval unit which retrieves information including the one or more keywords selected by the retrieval keyword selection unit from the data base identified by the retrieval instruction issue unit.