PURPOSE: To finish casting operation for each strand at the same time and to shorten the casting time by distributing remaining molten steel as necessary casting quantity to each strand, dividing an auto-stop velocity control term into four terms and adjusting casting start time and casting velocity to each strand.

CONSTITUTION: The remaining molten steel is distributed to each strand as necessary casting quantity, and also casting in the same strand is divided into four terms, and patterned, such as the first changing velocity term T*, the first constant velocity term T1, the second changing velocity term T** and the second constant velocity term T2. Next, a changing velocity ratio of the first changing velocity term and the second changing velocity term for the same strand is regulated to the same value v', and a term T1 of the first constant velocity term and a term T2 of the second constant velocity term between strands are regulated to the same term for each. And, a casting velocity VSP2 of the second constant velocity term is presetted and the starting time of the term T1 of the first constant velocity term and this constant velocity is adjusted to each strand, and so the castings for all strands are stopped at the same time for each strand and the casting operation is perfectly automized.