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.
Affleck was in
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.
According to sources, security informed Affleck he had been deemed an "advantaged player" and was no longer allowed to play blackjack at the Hard Rock. We're told security had spotted Affleck counting cards ... a gambling strategy that involves counting card values to decrease betting risk.
Counting cards isn't technically illegal, but it can get you kicked out of a casino -- which is exactly what happened to Affleck. We're told security arranged for a car service to take him back to his hotel.
FYI, Affleck is a well-known card shark -- back in 2001, he reportedly amassed $800,000 in blackjack winnings (at the Hard Rock now less) by playing three $20,000 blackjack hands at once.
Check out the whole story at TMZ.