PURPOSE: To obtain a hollow stock having a smooth inside surface characteristic with high accuracy by projecting a directional energy beam to the inside surface of the high-temp. hollow stock right after casting and melting and dropping the projecting part of the inside surface downward at the time of continuous casting of the hollow stock.

CONSTITUTION: A molten metal is received in a tundish 20 and a stopper 22 is risen to pour the molten metal into a control tundish 15. A slat conveyor 1 begins to move thereafter and the molten metal beings to solidify from the outside by contacting segments 2. The thickness is fixed at the point where the solidified metal emerges from the molten metal surface. The slat conveyor 1 is sealed by a nozzle 10 and a sealing chip 11 on the lower side of the casting mold to prevent leakage. The inside wall surface of the hollow stock pipe 3a right after the casting has projections and ruggedness, but a laser beam 51 generated by a generator 50 is projected from a scanning controller 52 to the wall to melt and drop the projecting parts of the inside wall by which the inside surface is smoothed with high accuracy. The cast hollow stock pipe is cut by a flying cutter 40 and is shifted; thereafter the pipe is turned over 90° to a horizontal position and is carried by a table 60.