1. A method of searching audio files in a portable audio player in combination with an automobile audio system, comprising the following steps of: reading meta-tag data associated with each audio file and producing voice data files for information retrieved from the meta-tag data; creating a play list that lists the voice data files produced based on the meta-tag data in an predetermined order where each of the voice data files and audio files is accompanied by address data; storing the play list and the audio files in the portable audio player; connecting the portable audio player with the automobile audio system for sending the voice data files in the play list and the audio files to the automobile audio system and receiving command signals from the automobile audio system; generating speech sounds that successively and automatically read aloud the data in the voice data files in the play list by the automobile audio system in a predetermined order and speed; accepting user's commands made in response to the speech sounds where the user's commands are transmitted through the automobile audio system to the portable audio player; and searching an audio file in the portable audio player based on the user's commands; wherein the speech sounds generated from the automobile audio system include a series of information on audio files so that a particular audio file is specified when both the information on the particular audio file is announced by the speech sounds and the user's commands are issued.