In The AV system, to produce a realistic sound effect is very difficult because the distance between stereo speakers is very narrow. Many signal processing method of widening the sound image for spatial impression have been studied. Most of the typical methods of widening the sound image are related to the phase shifting. but this method was not effective in the concrete wall structure with high reflectivity. In this paper, we proposed an effective method of extending stereo sound image using Precedence Effect and reflected sound. In experiments we confirmed the usefulness of the method for extending stereo sound image of a conventional AV system in wider listening area of a room.