Provided is an information retrieval system for car navigation systems that allows a vehicle occupant to designate a destination both easily and quickly. Each address is given as a combination of a plurality of strings of characters, each string corresponding to one of a plurality of search hierarchy levels, and the character strings are stored in a storage unit. If a current hierarchy level does not include any candidate of data that corresponds to a character entered by a user on an interface unit, a character type data search unit retrieves candidates from a next lower hierarchy level. Thereby, even if the use does not know a part of an address, the vehicle operator is able to successfully reconstruct the full address and enter a destination in an unambiguous manner. Such a candidate or candidates may be displayed on the monitor in combination with the corresponding data of the next higher hierarchy level. Alternatively, after the candidate or one of the candidates is selected by the user, corresponding candidates of data in the next higher hierarchy level may be displayed on the monitor.