Abstract. Indirect measurement method doesn't require a number of sensors and a large amount of labor. It is necessary to evaluate the comparable applicability to the direct measurement approach. This study investigates the validity of damage detection method using output-only measurement by indirect approach. The damage is detected using the curvature of power spectral density evaluation and proper orthogonal modes (POMs) of the responses data collected by experiments. The sensitivity of damage detection using time response and frequency response is compared through the beam test. It is illustrated in experiments that the indirect method can be widely utilized despite of the existence of external noise.