Ghazni governor's office said 12 of the wounded are female students of Ghazni University which is located on the outskirts of the provincial capital.
A bomb went off inside a classroom in eastern Ghazni province, wounding at least 19 university students, an official said on Tuesday.
Arif Noori, the spokesman for the provincial governor, says 12 of the wounded are female students.
The attack took place in Ghazni University, located on the outskirts of the provincial capital, the city of Ghazni.
Noori added that two of the wounded are in critical condition.
No one immediately claimed responsibility for Tuesday's attack.
Last month a magnetic explosive device attached to a minibus belonging to the same university detonated, killing the driver.
Noori says five students were also wounded in that blast.
At least 14 people, including a child, were killed and 37 wounded on Monday when a bomb hit a bus carrying army recruits in Jalalabad in eastern Afghanistan.
There was no immediate claim of responsibility, but Jalalabad is the scene of frequent attacks by the Taliban and Daesh terror group.