A cell culture apparatus includes a culture tank having an inlet and an outlet, a culture-medium supplying unit that supplies a culture medium to the culture tank through the inlet, and a culture-medium discharging unit that discharges the culture medium through the outlet. The culture tank includes a division wall that can divide the internal space in a direction of gravity into an upper space and a lower space. The outlet opens into the upper space, and the division wall enables switching between a state where the internal space of the culture tank is divided into the upper space and the lower space and a state where the upper space and the lower space are in communication with each other.