In a color polymorphic snake, Elaphe quadrivirgata, adults exhibit distinct color patterns such as striped, pale-striped, non-striped, banded, and melanistic morphs. To evaluate a heredity model of color pattern polymorphism, we examined correspondence of color morphs between mother snakes and their offspring based on the quantitative evaluation of individual variation in stripe pattern vividness with digital image analysis of skin coloration. Striped, pale-striped, and non-striped morphs were recognized in adult E. quadrivirgata, but the cluster analyses revealed only two groups of hatchlings, which were characterized by the presence and absence of the stripe pattern. Because the stripes of E. quadrivirgata are expected to become vivid with growth but do not fade, hatchlings categorized as the striped morph will become the striped morph in adults, and pale-striped and non-striped morphs will differentiate from the non-striped group of hatchlings after a certain period of growth. Observed frequencies of striped and non-striped neonates hatched from the clutches laid by striped, pale-striped, and non-striped females supported the assumption that the striped/nonstriped pattern polymorphism follows the rule of incomplete-dominance heredity model of one locus with two alleles and that the striped morph is dominant over the non-striped morph.