In dictionary retrieval processing by the electronic dictionary, if a headword matching a retrieval object word is not stored in a built-in dictionary data, the retrieval object word is registered in the form of a network-dictionary retrieval object listing. If a network dictionary retrieval is performed through connection to the dictionary server, a dictionary storing the registered retrieval word is retrieved in the dictionary server, is transmitted to the electronic dictionary, and is displayed. When the displayed dictionary in the network dictionary retrieval is selected, dictionary data is retrieved from the target of the selected dictionary, the dictionary contents corresponding to the retrieval word retrieved in the dictionary server is transmitted to the user electronic dictionary and is displayed. When update of a dictionary is instructed, data of the dictionary is transmitted and downloaded into the dictionary server, and built-in dictionary data is thereby updated and stored.