To prevent the production of the burn-on materials by insufficient cooling of the bottom segment of a spherical ladle and the outside surface of a ladle body and to lessen the erosion and crack of the ladle even if residual molten steel increases in the slag in the ladle body by accelerating the cooling at the bottom of the ladle and the outside surface of the ladle body.

The ladle body 1 integrally provided with a cylindrical ladle base 7 forming a vent space in the lower part of the spherical ladle bottom 2 is placed in the prescribed position of a heat resistant floor 6 and coolant is supplied from many fluid supply ports 11 for cooling the ladle bottom disposed in the heat resistant floor which is a region on the inner side of the cylindrical ladle base 7, by which the spherical ladle base 2 is forcibly cooled. The coolant discharged from the many holes 8 for ventilation disposed on the outer periphery of the cylindrical ladle base 7 is guided between many longitudinally long projections 10 disposed on the outside surface of the ladle body 1, by which the outside surface of the ladle body 1 is cooled.