The attacker concealed the bomb inside a bag of beans and exploded in the middle of a crowd in Kolofata, according to a source close to the security services.
A police source in the region confirmed the attack to AFP.
Boko Haram, a militant Islamist group, has been blamed for repeated assaults on Kolofata, including one particularly brazen operation in July 2014 that involved kidnapping the wife of the country's deputy prime minister, Amadou Ali.
Since its emergence eight years ago, Boko Haram, active in countries bordering Lake Chad (Nigeria, Cameroon, Niger and Chad), has killed at least 20,000 people.