To provide a method of manufacturing a high pressure-tight heat transfer tube with internal grooves, by which a heat transfer tube with the internal grooves which has thick wall thickness and the high angle of twist of the internal groove can be manufactured.

By arranging a floating plug 8 and a plug 9 with a groove connected to the floating plug 8 in the inside of a base material tube 2 having a diameter larger than the outside diameter of the tube which is tried to obtain and, on the outside of the base material tube 2, a drawing die 3, a pressurizing means 4 and a rotary swager 6 are arranged in order along the drawing direction of the base material tube 2. The base material tube 2 is drawn to reduce the diameter of the base material tube 2 with the drawing die 3 and also lock the floating plug 8 inside the drawn base material tube 2. The grooves are transferred on the inner surface of the base material tube 2 in the position of the plug 9 with the groove by pressurizing the base material tube 2 by the pressurizing means 4 and the base material tube 2 is thickened and reduced in diameter with the rotary swager 6.