Continuous casting method of cast slab

A continuously casting method including arranging temperature measuring elements according to specified conditions, selecting as evaluation targets for temperatures of copper plates on a wide face of mold values measured by the temperature measuring elements arranged closer to a center in a width direction of a cast slab than short sides of the cast slab under continuous casting at levels of 50 mm or more lower in a slab withdrawal direction than a meniscus of a molten steel in a mold, and adjusting a casting condition such that a standard deviation of the values measured over the width direction of the copper plates on the wide face of mold at a same level in the slab withdrawal direction is 20° C. or lower.