This paper proposes the method that evoked potentials stimulated by object colors are analyzed and examined on the phenomemon of color sensory. The method which is used to estimate the signal is time-varying. filtering (TVF). At the results of experiment which used object colors, it is shown that color sensory times of red are within the range of 0.0~0.25[sec], those of yellow are within the range of 0.25~0.55[sec], and those of blue are within the range of 0.55~0.75[sec]; they are inclined to sequence in accending order as red, yellow, and blue.