A cell separation container (10; 310) that separates a cell from a tissue using a treatment liquid, the cell separation container (10; 310) comprising: a collection chamber (20; 320) for collecting at least one of the treatment liquid and the cell; a tissue holding chamber (30; 330) disposed above the collection chamber (20; 320) and including a pouring inlet through which the treatment liquid is poured; a filter (40; 340) disposed as the entirety or part of a structure for partitioning the collection chamber (20; 320) and the tissue holding chamber (30; 330) from each other, the filter (40; 340) being capable of holding the tissue and allowing the cell to pass therethrough; and an air pressure adjusting mechanism (60, 70; 360, 370) capable of switching between a process of holding a treatment liquid poured into the tissue holding chamber (30; 330) without causing the treatment liquid to pass through the filter (40; 340) and a process of ejecting a treatment liquid poured into the tissue holding chamber (30; 330) to the collection chamber (20; 320) by causing the treatment liquid to pass through the filter (40; 340), the switching being achieved by adjusting inflow and outflow of gases in the collection chamber (20; 320) and the tissue holding chamber (30; 330), wherein the air pressure adjusting mechanism (60, 70; 360, 370) includes a first air pressure adjuster (60; 360) configured to adjust inflow and outflow of the gas in the collection chamber (20; 320), the first air pressure adjuster (60; 360) being disposed in the collection chamber (20; 320), and a second air pressure adjuster (70; 370) configured to adjust inflow and outflow of the gas in the tissue holding chamber (30; 330), the second air pressure adjuster (70; 370) being disposed in the tissue holding chamber (30; 330). a collection chamber (20; 320) for collecting at least one of the treatment liquid and the cell; a tissue holding chamber (30; 330) disposed above the collection chamber (20; 320) and including a pouring inlet through which the treatment liquid is poured; a filter (40; 340) disposed as the entirety or part of a structure for partitioning the collection chamber (20; 320) and the tissue holding chamber (30; 330) from each other, the filter (40; 340) being capable of holding the tissue and allowing the cell to pass therethrough; and an air pressure adjusting mechanism (60, 70; 360, 370) capable of switching between a process of holding a treatment liquid poured into the tissue holding chamber (30; 330) without causing the treatment liquid to pass through the filter (40; 340) and a process of ejecting a treatment liquid poured into the tissue holding chamber (30; 330) to the collection chamber (20; 320) by causing the treatment liquid to pass through the filter (40; 340), the switching being achieved by adjusting inflow and outflow of gases in the collection chamber (20; 320) and the tissue holding chamber (30; 330), wherein the air pressure adjusting mechanism (60, 70; 360, 370) includes a first air pressure adjuster (60; 360) configured to adjust inflow and outflow of the gas in the collection chamber (20; 320), the first air pressure adjuster (60; 360) being disposed in the collection chamber (20; 320), and a second air pressure adjuster (70; 370) configured to adjust inflow and outflow of the gas in the tissue holding chamber (30; 330), the second air pressure adjuster (70; 370) being disposed in the tissue holding chamber (30; 330). <EOS>