The present invention relates to a component separator capable of guaranteeing the purity of a subject component such as isolated blood or stem cells while simplifying a process compared with a conventional technique, and preventing air contamination during a component separation process, the component separator comprising: a hollow main body having a communication pipe, through which a body fluid communicates, formed at one end portion, and a main body female screw part disposed at the other end portion; a plunger for varying a main body space while moving forward and backward inside the main body; and an operation member having a pressing tube having a pressing male screw part capable of being screwed with the main body female screw part, and a plunger coupling tube having a tube screw screwed with a plunger screw part at the lower part of the plunger by coming into contact with or retracting from the inside of the pressing tube.