According to a report by the English-language Turkish newspaper Today's Zaman, the blast on the Erzurum-Kars highway on Saturday also left two people injured.
The soldier, along with a military unit, had been searching the area for mines after the PKK erected barricades on the highway in Kagızman district of Kars Province late on Friday.
The latest fatality comes amid Ankara’s ongoing airstrikes against the PKK positions in northern Iraq, near the border.
The Turkish military has also allegedly been striking positions held by the ISIL Takfiri militants in northern Syria.
The airstrikes began in the wake of the July 20 deadly bomb attack in the southern Turkish town of Suruc, not far from the border with Syria and close to the Kurdish town of Kobani in Syria.
The official Turkish news agency, Anatolia, on Saturday said, without giving a source for the figure, that the airstrikes have so far taken about 260 lives on the part of the PKK. The militant group, however, says the number is much lower.
The PKK has been engaged in a militancy in southeastern Turkey for decades in a bid to gain self-rule.