The explosion occurred on Monday as the family was heading home in a minivan after a shopping trip in Ghazni province, a provincial spokesman said.
"The minivan hit a landmine planted by the Taliban, killing seven members of a family, including three children, three women and one man," Shafiqullah Nang told AFP.
Qasem Disiwal, district chief of Andar, where the explosion occurred, confirmed the incident saying the area was heavily mined by the Taliban after they retreated following an Afghan army operation.
No group has so far claimed responsibility for the blast, but roadside bombs have been a weapon of choice for the Taliban in their their battle against the US-backed government and foreign forces.
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The bombs often target Afghan security forces, but they have also taken a heavy toll on civilians.
The number of civilians killed and wounded in Afghanistan jumped 22 per cent in 2014, a recent UN report said, as NATO troops withdrew from combat.
The United Nations Assistance Mission in Afghanistan attributed the rise to an intensification in ground fighting, resulting in a total of 10,548 civilian casualties last year.
The Taliban, waging a deadly insurgency since they were ousted from power in late 2001, warned that the announcement would damage any prospects of peace talks as they vowed to continue fighting.
Afghan forces are bracing for what is expected to be a bloody summer push by the Taliban.