The 29-year-old "Mean Girls" star said current drugs laws need to be relaxed in the UK, reported The Independent.
"(Cannabis) is wonderful thing, and lots of people use it responsibly, and it should be legal," she said.
The actress stars in the comedy "Ted 2" in the role of Samantha Leslie, who is partial to the occasional hit on a bong. Seyfried said alcohol poisoning kills more people yet "pot is stigmatised."
"I don't understand how people can die all the time from alcohol poisoning. Yet pot is so stigmatised. They could have put a bong in every scene as far as I'm concerned," Seyfried said.