The 2003 All Japan Grand Touring Car Championship was the eleventh season of Japan Automobile Federation GT premiere racing. It was marked as well as the twenty-first season of a JAF-sanctioned sports car racing championship dating back to the All Japan Sports Prototype Championship. The GT500 class champions of 2003 were the #23 Xanavi NISMO Nissan Skyline GT-R team driven by Satoshi Motoyama and Michael Krumm and the GT300 class champions were the #3 Hasemi Motorsports Nissan Fairlady Z driven by Masataka Yanagida and Mitsuhiro Kinoshita, neither of which had won a single race during the course of the season.