The method for absolute quantitation of 1H MRS in a human brain at high B0 field was proposed. A water phantom as a concentration reference and a human brain area measured separately. The ratio of the reception sensitivities between uniform areas in the phantom and in the human brain can be computed from measured B1+s. The ratio between the VOI and the uniform area in the human brain can be computed by our previously reported ratio map method. Then, concentration in the VOI can be calculated. Our method was demonstrated in the phantom experiments.