It is an established theory that the phenomenon of color contrast is brought about because of the after image of opponent color chich is created against the color that the color wave perceives when a color is reflected on eyes. Now the opinion of the writer of this study is that the term “after image of opponent color”, which is used in the existing theory, should be turned into “anti-image of opponent color” and it is supported by followings ; First, as the human body, when infected by disease germs, generates anti-germ or antibody physiologically with the innate self-defense system against the games, in other words, each organization of the human body hasitsown balance control function, so the retina, corresponding to the stimulus of color reflected on itself, forms the image of opponent color. Secondly, there is a great conceptional difference between the term “anti-image” and “after-image” for the moment of occurrence, because the word “anti” involves the meaning of simultansity while “after” contains the meaning of time difference. At the moment that a light stimulates the retina appears simultaneously the anti-image of opponent color for physiological balance, then it is mixed with the real color on eyes and neutralized into grey. Here the spreaded part of the anti-image of opponent color works on adjacent color with after-effect, generating the phenomenon of so called color contrast. And such a theory might be much easier for students to understand.