A component separator comprising: a hollow main body which includes a communication pipe formed at one end portion thereof to allow a flow of body fluids therethrough and a main body female screw part disposed at the other end portion; a plunger which is installed inside of the main body, and has a plunger screw part formed in a center of a plunger lower portion which is integrally formed with a plunger head; and an operation member which is installed inside of the main body to move the plunger forward and backward so as to vary a main body space, wherein the operation member comprises: a hollow pressing tube which has a pressing male screw part formed on an outer surface thereof so as to be screwed with the main body female screw part and a pressing tube protrusion formed at an end portion thereof on the plunger side, wherein the plunger is moved forward by rotating the hollow pressing tube; and a plunger coupling tube which is slidably inserted inside of the pressing tube, and has a tube screw which is formed at a tip thereof and which is screwed with the plunger screw part in a state in which an end portion thereof on the plunger side is engaged to the pressing tube protrusion, wherein the pressing tube protrusion is disposed at a front end of the pressing male screw part so as to contact with a bottom of the plunger lower portion, wherein thread directions of the main body female screw part and the pressing male screw part are opposite to thread directions of the plunger screw part and the tube screw. a hollow main body which includes a communication pipe formed at one end portion thereof to allow a flow of body fluids therethrough and a main body female screw part disposed at the other end portion; a plunger which is installed inside of the main body, and has a plunger screw part formed in a center of a plunger lower portion which is integrally formed with a plunger head; and an operation member which is installed inside of the main body to move the plunger forward and backward so as to vary a main body space, wherein the operation member comprises: a hollow pressing tube which has a pressing male screw part formed on an outer surface thereof so as to be screwed with the main body female screw part and a pressing tube protrusion formed at an end portion thereof on the plunger side, wherein the plunger is moved forward by rotating the hollow pressing tube; and a plunger coupling tube which is slidably inserted inside of the pressing tube, and has a tube screw which is formed at a tip thereof and which is screwed with the plunger screw part in a state in which an end portion thereof on the plunger side is engaged to the pressing tube protrusion, wherein the pressing tube protrusion is disposed at a front end of the pressing male screw part so as to contact with a bottom of the plunger lower portion, wherein thread directions of the main body female screw part and the pressing male screw part are opposite to thread directions of the plunger screw part and the tube screw. a hollow pressing tube which has a pressing male screw part formed on an outer surface thereof so as to be screwed with the main body female screw part and a pressing tube protrusion formed at an end portion thereof on the plunger side, wherein the plunger is moved forward by rotating the hollow pressing tube; and a plunger coupling tube which is slidably inserted inside of the pressing tube, and has a tube screw which is formed at a tip thereof and which is screwed with the plunger screw part in a state in which an end portion thereof on the plunger side is engaged to the pressing tube protrusion, wherein the pressing tube protrusion is disposed at a front end of the pressing male screw part so as to contact with a bottom of the plunger lower portion, wherein thread directions of the main body female screw part and the pressing male screw part are opposite to thread directions of the plunger screw part and the tube screw.