The generation of a wide-range THz wave is investigated from a photoconductive antenna excited using a chaotic oscillation multimode semiconductor laser with optical delayed feedback by an external mirror. The stable THz wave is obtained from the multimode-laser diode excited photoconductive antenna by using a laser chaos. For a high sensitive detection, a metal V-grooved waveguide (MVG) is also used. About 10 times high amplitude signal is obtained using laser chaos. The signal is also increased about 1.6 time using MVG compared to Si lens. As the MVG gap is narrower from 200 to 20[μｍ], the detected signal is increased about twice.