The purpose of the present invention is to develop a culture method/system which enables the separation and culture of a cell in a completely closed system. The present inventors have achieved the above-mentioned purpose by providing a culture method, a culture system and a culture apparatus, in all of which a body fluid containing a blood cell is mixed with an erythrocyte-aggregating agent in a closed system in an aseptic manner, then allowing the resultant mixture to stand to thereby precipitate an erythrocyte, and then injecting a lymphocyte-containing buffy coat layer into a closed culture apparatus in a closed manner, thereby culturing the blood cell.
