A culture system has a culture bag for suspending and culturing pluripotent stem cells in a culture medium; a waste liquid container for storing used culture medium that is connected to the culture bag; a fresh medium container for storing a fresh culture medium that is connected to the culture bag; three-way stopcocks for switching flow channels from the culture bag to the waste liquid container or the fresh culture medium container, etc.; a trap portion for trapping the pluripotent stem cells in the culture medium in the flow toward the waste liquid container side; and a filter portion for subculturing that is formed in fourth and fifth flow channels in parallel to a first flow channel. The first flow channel connects the trap part to the culture bag, and has a mesh by which a cell mass of the pluripotent stem cells can be divided. A pump is used to pump the liquid in the individual flow channels.