STRA6 is a cell membrane receptor for a complex of retinol, a type of vitamin A (VA), and RBP4, and promotes VA uptake into a cell. It is known that VA has many physiological functions. In Japanese black cattle, to improve marbling, a fattening is performed by VA restriction. Therefore, polymorphisms in STRA6 gene can affect marbling and other carcass traits. We searched for polymorphisms of STRA6 gene in Japanese black cattle, and 7 SNPs were detected. Of these SNPs, only c.866A>G（p. Q289R） was a non-synonymous SNP. Genotyping of the c.866A>G was performed with 1,235 fattened Japanese black steers, and an association between the SNP and major carcass traits were analyzed. The analysis indicated that the mean BMS of G/G cattle was significantly higher than other genotypes, A/A and A/G (p<0.05). Furthermore, to make equal the genetic background among individuals, A/A cattle and their half-sibs, a total of 150, were selected from the 1,235 cattle. Even in the selected cattle, the mean BMS of G/G cattle was significantly higher than other genotypes (p=0.05). STRA6 p.Q289R was located around the VA transport pore. Moreover, amino acid residues, which the p.Q289R was adjacent, had been reported that substitution of these amino acids impedes vitamin A transport. Therefore, it was suggested that c.866A>G affects the marbling formation by reducing the function of STRA6 and promoting adipocyte differentiation without significantly impairing physiology.