Abstract: The present invention may include an upper cap having an opening/closing member for opening and closing an inlet through which a blood is injected; a main body housing having an open upper end outer surface thereof assembled with the upper cap, and having an inner space in which the blood is filled with; an adjustment housing that is coupled to the main body housing to seal the open lower end of the main body housing, and is movably assembled with respect to the main body housing so that a buffy coat layer is positioned on a neck portion; and a side cap fixed to the neck portion by forming a needle hole through which an end of an injection needle for extraction enters and exits in area corresponding to a sealing member to seal an extraction hole formed through the neck portion.