Subjective evaluation on printed paper was carried out in order to fix important specifications for the reflective LCD, with emphasis on the luminous reflectance and contrast ratio of monochromatically printed paper. As a result, an important parameter P was extracted and found to express the visibility of the reflective LCD. The definition of the parameter P is given and the usefulness of the P will be discussed in connection with the visibility. Using this parameter, the intuitive visibility was expressed as a qualitative function of brightness and contrast ratio. And the way to be followed in the development of the reflective LCD was identified.