PURPOSE: To set positions of the surfaces for pressing molds quickly and accurately with simple operations by bringing the preceding ends of reference pins for centering into abutment on the side surfaces of copper plates of short side and setting the positions of the surfaces for pressing the molds in the root end positions of the pins.

CONSTITUTION: The preceding ends of reference pins 2, 2 for centering are brought into abutment on the side surfaces of mold copper plates 4, 4 of short side in tight contact with the mold copper plate 3 of long side of a mold 6. Then, the root ends of the pins 2, that is, the distance between the surface for pressing the mold and the inside surface of the plate 3 is set at the distance D between the reference plane L of the mold and the ingot guide surface of strand guides. Thus if the mold 6 is placed on a molding table 7 and the root ends of the pins 2, 2 are brought into abutment on the surface L provided to the table 7 by pressing machine bolts 8, the inside surface of the plate 3 is positioned to the ingot guide surface of the strand guides.