PURPOSE: To obtain the tailless nozzle which improves the effect of preventing tail generation and allows easy production.

CONSTITUTION: A cylindrical flow passage having slender sectional shape in the state of forming crescent-shaped sectorial step parts 4 on both sides of a deformed dome-shape hollow surface 3 formed with nearly semicircular sloped plane parts 2 to face each other is provided on the upstream to the above- mentioned hollow surface 3. Further, straight corner angle parts 6 of an obtuse angle are provided symmetrically in parallel in a lateral direction in the successive connecting part of the end edge of the sloped plane parts of the surfaces 3 and the front end of the cylindrical flow passage or near this successive connecting part. A V-shaped groove intersecting from the front is inscribed to the surface 3 at about the depth at which the valley thereof coincides with the corner angle parts 6. Not only the tail generation is effectively prevented by the above-mentioned constitution but also the production is facilitated as the permissible range of the deviation in the depth and lateral direction of the V-shaped groove is wide.