Tomato hypocotyl can generally be one of two colors, purple or green. Genetically, this trait is controlled by a single dominant gene. Hypocotyl tissue specific color expression is one of many visible genetic marker sources used to select tomato progeny. However, the visible marker does not show a clear distinction between homozygous genotype and heterozygous genotype from the breeding lines. Therefore, to identify a hypocotyl pigmentation related marker, we screened DNA polymorphisms in thirteen tomato lines showing purple or green hypocotyls. The markers used for screening consisted of primer set information obtained from anthocyanin related genes, conserved ortholog set II (COS II) marker sets localized near anthocyanin related genes, and restriction fragment length polymorphism (RFLP) markers localized near COS II markers, which produce polymorphisms between purple and green tomatoes. One primer from a RFLP fragment resulted in a polymorphism on agarose gel electrophoresis. From the RFLP fragment, a cleaved amplified polymorphic sequence (CAPS) marker was developed to distinguish between purple and green hypocotyls. The genotypes of 135 $F_2$ individuals were analyzed using the CAPS marker, and among them, 132 individuals corresponded to the phenotypes of hypocotyl pigmentation.