A container constitutes a platelet separator (tertiary separator separating a platelet-containing component into platelets and another component by applying a centrifugal force. An inflow portion configured to allow the platelet-containing component to flow into a third chamber and configured to allow a platelet additive solution to flow in and an accommodating portion accommodating the platelets are disposed in the container. Also disposed in the container are an opening of an outflow port allowing at least an outflow of the other component and an opening of a recovery port disposed in a place different than the opening and recovering the platelets and the platelet additive solution.
