The US drone hit a vehicle in South Waziristan region, which borders Afghanistan.
The US has expanded its airstrikes in Pakistan since President Barack Obama took office in 2009.
The US often carries out such attacks on Pakistan's tribal regions, claiming that the militants are their target.
But locals say civilians are the main victims of the unauthorized US strikes. Hundreds of people have been killed in the attacks.
There have also been numerous demonstrations across Pakistan against the US drone attacks.
The issue of civilian casualties has strained relations between Islamabad and Washington with the Pakistani government repeatedly objecting to the attacks.
The United Nations says the US-operated drone strikes in Pakistan pose a growing challenge to the international rule of law.
Philip Alston, UN special envoy on extrajudicial killings, said in a report in late October 2010 that the attacks were undermining the rules designed to protect the right of life.
Alston also said he fears that the drone killings by the US Central Intelligence Agency could develop a "playstation" mentality.
Who controls these drones and where do they control them from? I know a man who claims to be a drone controller as he is in the Air force and has the mentality of a religious zealot. I have known him for 29 years from the age of fourteen when he was a happy surfer beach kid. What he has become and what I have laid witness too is painful and alarming. His conformity and lack of empathy reflects in his eyes and manners. I know not what he is. He too, has become a drone.