"Boko Haram terrorists attacked defense force positions in Kaiga Kindji early this morning," a military spokesman said Wednesday.
He added that the attack also injured 11 other soldiers, but had been "vigorously" thwarted, Presstv Reported.
Chad is a member of a multinational task force combating Boko Haram across its border with Nigeria, Niger and Cameroon. The force has been created with the aim of preventing a spillover of the militancy to those countries from Nigeria.
Boko Haram has been largely pushed out of its main strongholds in northern Nigeria, according to the country’s military and government. The group, however, is still active in its Sambisa Forest enclave in Borno and launches sporadic attacks on civilians and security forces from there.
More than 20,000 people have been killed and hundreds of thousands displaced in more than eight years of insurgency by Boko Haram in Nigeria, Chad, Cameroon and Niger. The group pledged allegiance to the Takfiri Daesh group in 2015.
The United Nations has warned that areas affected by Boko Haram face a humanitarian crisis.
Earlier this month, a Chadian soldier was killed in a mortar attack launched by Boko Haram on a military camp in Litri, near the border with Nigeria.
In late September, six people, including two soldiers, were killed in another Boko Haram attack on the Chadian shores of Lake Chad, in which 17 of the assailants were shot dead by the army.