The present invention relates to a buffy coat extraction kit including: a kit body having a cylindrical plasma part that has an internal volume for forming a plasma layer, a cylindrical buffy coat part which extends in the longitudinal direction while communicating with the lower part of the plasma part and has a diameter smaller than the diameter of the plasma part and an internal volume for forming a buffy coat layer, and a cylindrical erythrocyte part which extends in the longitudinal direction while communicating with the lower part of the buffy coat part and has a diameter larger than the diameter of the buffy coat part and an internal volume for forming an erythrocyte layer, wherein the free end part of the plasma part and the free end part of the erythrocyte part are respectively opened a lower packing movably accommodated in the erythrocyte part while maintaining an air-tight state and a pusher moving the lower packing.
