To easily cut an ingot at on-site by inserting a mold for recessed part formation into molten metal after pouring the molten metal into a mold, shifting the mold together with the molten metal and removing the mold for recessed part formation after solidifying the molten metal.

When the mold 1 supplied with the molten metal is shifted just below a device provided with the mold 2 for recessed part formation, a dog 20 is brought into contact with a mold conveying wheel 14, and a limit switch is worked to detect the mold 1. Based on this detected signal, the mold 2 for recessed part formation is descended and a V-shape part at the tip part of the mold 2 for recessed part formation is inserted into the molten metal. Into the mold for recessed part formation, the cooling air is blown from an air nozzle 13. The shifting carriage disposed with the mold 2 for recessed part formation, is shifted at the same speed as the shifting speed of the mold 1. When the molten metal in the mold 1 is solidified and the ingot is formed, the mold 2 for recessed part formation, is pulled up and removed from the ingot. The ingot is formed as the sound state and the recessed part 4 is formed at the removed track of the mold 2 for recessed part formation.