39 linked to the end of the flexible tube 20 and push or pull the connector 3 39 when the piston 4 is completely pulled up the protrusion 23 formed on the upper inside of the cylinder 8 is fitted in the concave groove 8b of the piston 4 therefore the piston 4 becomes immovable and when the piston 4 is completely pushed down the protrusion 24 formed at the lower inside of the cylinder 8 is fitted in the concave groove 8b of the piston 4 so the piston 4 again becomes immovable the flexible tube 20 should have proper hardness to not be crushed when the piston 4 is pushing down or pulling up by the transfusion line connector 3 39 fig1 through 18 illustrate a third embodiment of this invention one side of the resin cylinder 30 of the injectant container 13 and the resin needle set 1 is connected to the injectant line linked up to the injectant regulator 14 and the connector 32 is screwed in the other side of the resin cylinder 30 of the resin needle set 1 in which the elastic body 33 is inserted and the needle cylinder 34 equipped with the metal needle 7 and the connector 32 are assembled to the cylindrical film shield 2 and the metal needle 7 having a vent hole 18 is protruded beyond the resin tube 9 penetrating the elastic material of the connector 32 and the same of the resin cylinder 30 when making an injection of blood or injectant remove the connector 32 from the resin cylinder 30 of the resin needle set 1 and inject the injectant by adjusting its flow speed by the injectant regulator 14 linked to the injectant line 15 connecting the injectant container 13 and the resin.