In the field sequential color(FSC)driving, it has been known that the eye tracking with the observer recognizes the color break-up. The color break-up has been evident by some evaluations, and it has also been known that the color break-up depends on the moving speed or the display frequency of the primary color light source. But the quantitative evaluation for its allowable color break-up is not enough. In this report, the novel color break-up model is originated, and it is found out that the model can be applied from the results of the subjective experiment. The model contains the observer's eyesight in addition above parameters.