The factory owners are suspected of ignoring cracks in the building and forcing their staff to work in the eight-story building, the BBC reported.
The Rana Plaza building in the Dhaka suburb of Savar fell Wednesday, killing at least 336 people.
About 3,000 people were believed to have been working in the building at the time of the collapse. Some 600 are still missing.
The owner of the plaza is reported to have gone into hiding.
Several relatives of the owner and two engineers have also been arrested, CNN reported.
Sajjad Hussein, a spokesman for an anti-corruption agency, said "thousands" of survivors had been treated at a local medical college hospital. Hussein said the need for blood was "acute" and there was a shortage of medicine.
Rescue workers pulled at least 24 people from the rubble Saturday morning. Police say more than 2,300 people have been rescued.
Officials said the rescue effort would end Saturday, setting off protests in four districts of Dhaka that police had to disperse with tear gas.