Manufacturing method for continuously cast product of steel

A manufacturing method for a continuously cast product of steel comprising the steps of:

• detecting a position of a crater end of the product by using a method for measuring a solidification state of the continuously cast product by a sensor arranged so as to be in non-contact with said product;
• and
• controlling at least one condition selected from the conditions of casting speed and quantity of secondary cooling water based on said detected position of the crater end, said method for measuring a solidification state of the continuously cast product comprising the steps of:
• transmitting transverse waves of electromagnetic ultrasonic waves to said product repeatedly in pulse units as a transmitting signal;
• receiving a signal after said transmitting signal propagates in said product as a receiving signal;
• and
• judging the solidification state of said product by averaging pulses and performing signal processing of the receiving signal so that the average number is not less than 16 times and not more than pulse cycles in which signal intensity after said averaging does not decrease.