The incident happened in the South Waziristan tribal region where thousands of troops have been hunting al Qaeda-linked militants this year.
"The vehicle overturned after the explosion, killing six soldiers and injuring several others," said military spokesman Major General Shaukat Sultan.
The blast occurred in the town of Kanigarram, a stronghold of the Mahsud tribe where troops and militants have clashed often in recent months.
Security forces have stepped up their campaign in the region to hunt down a tribal leader, Abdullah Mahsud, after he masterminded the kidnapping of two Chinese engineers in the region on October 9.
The vehicle plunged into a deep ravine after it hit the roadside mine, which was detonated through a remote control at Salweshtey area around 12 noon local time where the troops are busy in operation against al Qaeda militants and their local supporters, an army official, requesting not to be named, said.
No one claimed responsibility for the attack but the authorities usually blame the militants for such attacks.
Landmine blasts are common in the area as the militants are now targeting the soldiers by such roadside landmine blasts.