Another six soldiers were injured in the bombing blamed on the outlawed Kurdistan Workers' Party (PKK), news agency Anadolu said, AFP reported.
The attack was carried out using a handmade bomb that detonated as the armored vehicle drove by, the agency added.
The guard killed was part of a group of local residents who cooperate with Turkish security forces in the fight against the PKK, listed as a terror group by Ankara and its Western allies.
The latest attack came after three police officers were killed in an assault earlier Thursday on the police headquarters in the eastern city of Elazig.
Two more policemen and a civilian were killed in another car bombing on Wednesday night in Van, another city in the east which has a mixed ethnic Kurdish and Turkish population.
The PKK, which has been fighting a deadly insurgency against the Turkish state for three decades, appear to have intensified their attacks since the July 15 failed coup against Turkish President Recep Tayyip Erdogan.
Over 40,000 people have been killed since the group first took up arms in 1984 in a separatist rebellion led by now jailed leader Abdullah Ocalan.