A user enters a numeric string on a standby screen of a cellular telephone, and then presses a predetermined function key, the numeric string obtained by numerical conversion of a piece of registration information, in accordance with an assignment relationship indicated on numerical keys of the cellular telephone. A database in which numeric data obtained by the numerical conversion of a piece of registration information in accordance with the above-mentioned assignment relationship and the piece of registration information are associated with each other is previously held in the cellular telephone. The database is searched by using the entered numeric string as a search key, so that pieces of registration information associated with numeric data containing the numeric string are extracted. An exactly matching one of the extracted pieces of registration information is sorted in a high rank and displayed.