1. A method for searching for address book information by an apparatus, the method comprising: receiving a search request message for searching for address book information using preference information of a requesting client form the requesting client; in response to receiving the search request message, obtaining address information of a plurality of external directories and the preference information representing at least one external directory preferred by the requesting client from an external server; checking address information of at least one external directory form among the address information of the plurality of external directories based on the preference information and the address information; forwarding an external search request message to the at least one external directory using the address information of the at least one external directory; receiving an external search response message including an external search result searched by the at least one external directory from the at least one external directory; prioritizing the external search result and arranging the prioritized external search result; and forwarding a final search result including at least part of the arranged external search result to the requesting client, wherein the preference information further comprises information regarding application or non-application of a search preference to the search request of the address book information, information regarding application or non-application of the search preference to at least one external search domain corresponding to the at least one external directory, and information regarding application or non-application of the search preference for a dynamic search according to a user's location, and wherein the information regarding application or non-application of the search preference to the at least one external search domain comprises the at least one external search domain and a preference weight value per domain.