An apparatus for cell culture by perfusion comprising a cell culture tank for suspension culture, said cell culture tank having a suspension cell culture zone, a cell settling zone, an opening for discharging a spent culture medium from the settling zone and an opening for supplying a culture medium to the suspension culture zone, the suspension culture zone and the setting zone being separated by a partition therebetween in a manner to communicate with each other in the lower portion of the settling zone, and the settling zone being formed between the side wall of the cell culture tank and the partition. Another type of apparatus for cell culture having a unit in which main culturing and settling are carried out in a cell settling zone, and a multiunit cell culture apparatus having at least two culturing units which are stacked longitudinally are also described. A method for culturing cells by perfusion in the culture apparatus which comprises withdrawing a substantially cell-free culture medium from the settling zone and introducing a fresh culture medium into the suspension culture zone.