Magnetic investigation was carried out for low temperatures electronic phases in (EDT-TTF)(2)AuBr2, which undergoes an SDW transition at 16 k. In the SDW phase, we observed an abrupt change of H-1-NMR absorption line around 6 K where the H-1-NMR spin-lattice relaxation rate shows an anomalous second peak. The electronic phase is discussed by microscopic point of view.