The carbon content in molten steel is adjusted to be a value not lower than 0.001%, and a thin steel strip is made from this molten steel using a twin drum type continuous casting apparatus by means of direct casting. The thus obtained slab is given a reduction of not lower than 10%. The coagulated steel strip is cooled to a temperature not higher than the temperature determined by a function of the carbon content, cooling speed and ratio of reduction of in-line. After that, the steel strip is reheated and then cooled again to a temperature not higher than the temperature determined by the function of the carbon content. Then the cooled steel strip is coiled. In the above process, a metallic sheet, the surface of which is smooth and the metallic structure of which is fine, can be produced.