Disclosed is a blood ingredient separator capable of assuring purity of such as separated blood components or stem cells as well as preventing contamination by ambient air during the process of separating components, while simplifying the processes compared to the related art. The ingredient separator includes: a hollow body which includes a flow tube formed at one end portion thereof for communicating body fluids, and a stopper disposed at the other end portion thereof and a plunger which is movably installed back and forth in the body to vary a space between the flow tube and a top of the plunger thereof wherein the plunger has a collection portion formed on the top thereof, and a backward movement of the plunger is limited by the stopper.
