The 36-year-old actor - who was educated at the top private school Harrow - says he is sick of attacks on his privileged background.
The 'Tinker Tailor Soldier Spy' star, whose parents were actors, said that ''all the posh-bashing that goes on'' made him consider moving to the United States.
He told the Radio Times magazine: ''I wasn't born into land or titles, or new money, or an oil rig.''
But Benedict said that he had been ''castigated as a moaning, rich, public-school bastard, complaining about only getting posh roles''.
He continued: ''It's just so predictable ... so domestic, and so dumb... It makes me think I want to go to America.''
The star - who is to play an Edwardian aristocrat in BBC1 period drama 'Parade's End', said he enjoyed becoming a pin-up after 'Sherlock'.
He admitted: ''It puts a bit of a spring in your step. It's nice, you swagger a little bit, it's enjoyable.
''I've punched well above my weight this year. And that remains very much a secret ...
''I find it hysterically funny ... It's a giggle. I wield it with a massive smile.''