Ben Affleck's blackjack days are over at least at the Hard Rock in Vegas -- because he was just banned FOR LIFE from playing the game at the casino ... after security says they caught him counting cards, TMZ reports.
Affleck was in Sin City earlier this week with wife Jennifer Garner. We're told he planned the Vegas trip as a romantic getaway before he ships off to Detroit for several months to shoot his new Batman movie.
But things took an unromantic turn Tuesday night -- Hard Rock casino sources tell us, Affleck was playing blackjack at a high rollers' table when security swarmed.
See this story on www.tmz.com