Abstract: An information retrieval apparatus, method and memory medium storing a program therefor provide for storing, in a memory, identification information of information sources to be queried, in accordance with an information retrieval keyword, issuing inquiries to relevant information sources, based on respective identification information thereof stored in the memory, and updating the identification information stored in the memory based on retrieved information from the queried information sources. Each information source may be an information retrieval apparatus, all thereof interconnected in a local network and/or through the local network to a network outside of the local network.