The present invention provides a spiral groove machining device and a spiral groove machining method for tube. No scratch generates on the tube, and the spiral groove with a certain depth and uniform space can be formed on the tube with a smaller dimension. The spiral groove machining device for tube is provided with the following components: a core steel wire which can be inserted into the tube, a steel wire tensioning mechanism which can tension the core steel wire, and a core wire rotating unit which causes the tensioned core steel wire to rotate clockwise and counterclockwise together with the tube. Preferably the spiral groove machining device for tube is provided with a reel which rotates by means of the core wire rotating unit and can supply the tube that is guided out from a tube supply and discharge mechanism for winding. The spiral groove machining method for tube comprises the following steps: a steel wire tensioning step of tensioning the core steel wire that is inserted into the tube a tube winding step of clockwise rotating the tensioned core steel wire together with the tube for winding the wire on the tube a wire drawing-back step of counterclockwise rotating the core steel wire together with the tube for drawing back the wire that is wound on the tube and a tube detaching step of detaching the tube from the core steel wire.
