Continuous casting method of steel

A continuous casting method of steel of continuously casting a slab by using a vertical liquid bending continuous casting machine, the method comprising:

• while performing continuous casting by using an in-mold electromagnetic stirring device, applying an alternating-current moving magnetic field that moves in a width direction of a mold to molten steel inside the mold;
• inducing a swirling flow in the molten steel;
• and
• stirring the molten steel,
• wherein a travel speed U of the alternating-current moving magnetic field calculated by Formula (1) is in a range of 0.20 to 1.50 m/s:
• U=2τf (1)
• where, in Formula (1), U is the travel speed (m/s) of the alternating-current moving magnetic field, t is a distance (m) between magnetic poles of a coil of the in-mold electromagnetic stirring device, and f is a frequency (Hz) of an electric current that is applied to the coil of the in-mold electromagnetic stirring device,
• wherein the frequency of the electric current that is applied to the coil of the in-mold electromagnetic stirring device is in a range of 0.2 to 1.0 Hz, and
• wherein an effective value of a component in a thickness direction of the mold of a magnetic flux density of the alternating-current moving magnetic field is 0.008 T or greater and 0.030 T or less in terms of an average value in the width direction of the mold inside the mold where a position in a height direction of the mold is a central position in a height direction of the coil of the in-mold electromagnetic stirring device and where a position in the thickness direction of the mold is a position that is 15 mm from an inner surface of a long side of the mold.