The object is to provide a means for aseptically separating a suspending medium from a suspension. There is provided a device comprising at least the followings: a hollow fiber type separator for separating a liquid A from a suspension comprising an inlet and outlet for passing the suspension, which communicate with the inside of hollow fibers, and at least one discharge port for discharging the separated liquid A, which communicates with the outside of the hollow fibers； an aseptic connection connector for aseptically connecting a bag containing the suspension in a non-aseptic environment, which is connected to the inlet of the hollow fiber type separator； a drainage bag for storing the separated liquid A, which is connected to the discharge port of the hollow fiber type separator； and a collection bag for storing a suspensoid from which the liquid A has been separated, which is connected to the inlet or outlet of the hollow fiber type separator.
