Three Malian soldiers were killed when their vehicle hit a landmine in the central region of Mopti, officials say.
Two others were wounded and taken to a hospital, the defence ministry said in a statement.
No group has claimed responsibility for the device.
Mali has been threatened by various armed groups and has fought Islamist rebels in the north for a number of years.
The incident happened in Mondoro, next to the border with Burkina Faso, the statement said.
Al-Qaeda-linked militants have been fighting the army in northern Mali and France, the former colonial power in the country, intervened in January 2013 to stop their advance south to the capital.
But attacks across the country have increased recently, including a shooting at a hotel in the capital, Bamako, that left 22 people dead in November.
Militancy in Mali
- October 2011: Ethnic Tuaregs launch rebellion after returning with arms from Libya
- March 2012: Army coup over government's handling of rebellion; a month later Tuareg and al-Qaeda-linked fighters seize control of north
- June 2012: Islamist groups capture Timbuktu, Kidal and Gao from Tuaregs, start to destroy Muslim shrines and manuscripts and impose Sharia
- January 2013: Islamist fighters capture a central town, raising fears they could reach Bamako. Mali requests French help
- July 2013: UN force, now totalling about 12,000, takes over responsibility for securing the north after Islamists routed from towns
- July 2014: France launches an operation in the Sahel to stem jihadist groups
- Attacks continue in northern desert area, blamed on Tuareg and Islamist groups
- 2015: Terror attacks in the capital, Bamako, and central Mali