Laurent Rambaud was convicted Friday in the Valence court over the Dec. 20, 2010 killing of Ernest Pardo.
The 37-year-old Rambaud insisted he didn't mean to kill Pardo. He told police he was guarding a truffle patch on his land around nightfall when he was surprised by a man and a dog, and opened fire out of fear for his life.
Police say Pardo was known to sell the prized delicacy at local markets. He was holding a small pick.
The killing took place in Grignan, near one of France's largest truffle markets. Truffles sell for up to $1,000 per kilogram (2.2 pounds).