PURPOSE: To improve processing efficiency of parallel corrugated tube by accelerating sending of the tube, by forming helical corrugated projection streak shifting the phase each other on the inner circumference wall of corrugated DIE.

CONSTITUTION: The corrugated DIE 4 is attached on the flier 2 supported on the base stand 1 rotatably and eccentrically for rotating axis line. The plural helical corrugated projections 41A, 41B are formed on the inner circumference part of the DIE 4 shifting the phase at 180°. The DIE 4 is rolled along the outer circumference of the circular tube 10 by boring the projection 41A into the outer circumference wall of the tube 10 and rotating the flier 2 and then, the groove coresponding to the arc of the projection 41A, is formed. When the groove of about a half circumference is formed on the tube 10, the projection 41B shifted the phase at 180°, is bored into the tube 10 and the groove formation is continued. By the above apparatus, parallel corrugated tube is able to manufacture with a high efficiency by accelerating sending of the tube.