The blast was a grim reminder of the major challenge facing Iraqi forces three weeks ahead of the June 30 deadline for U.S. troops to withdraw from urban areas.
The bomb was attached to the minibus in the southern area of Abu Dshir, a Shiite enclave in the mainly Sunni neighborhood of Dora, police said.
The explosion left a crater at the entrance of the bus station where commuters were gathered to catch rides to different parts of the city.
An Associated Press photographer saw the charred hulk of the minibus and three other burned-out cars. Security forces sealed off the area while ambulances rushed the wounded to the hospital.
Police and hospital officials, who spoke on condition of anonymity because they weren't authorized to release the information, gave the death toll and said 24 people also were wounded.
Both districts have faced brutal sectarian bloodshed in past years but have seen a sharp decline in violence following a Sunni revolt against insurgent groups such as al Qaeda in Iraq and a Shiite militia cease-fire.
U.S.-Iraqi forces also increased their presence and cordoned areas off with concrete walls and checkpoints in the citywide push to quell the violence that pushed the country to the brink of civil war.
With the decline in violence, Iraqi authorities have taken down many of the concrete walls in a bid to restore a sense of normalcy in the capital.
But several recent high-profile bombings have raised concerns about the readiness of Iraqi forces to take over their own security.
The June 30 withdrawal date was provided for in the U.S.-Iraq security agreement that took effect this year. President Barack Obama plans to end U.S. combat operations by September 2010 and remove all U.S. troops from the country by Dec. 31, 2011.
Iraq's Shiite-led government insisted on a timetable for the withdrawal during last year's negotiations that produced the security agreement.