To suppress external flaws occurring from the difference in level of a base stock as a starting point even in the case a seamless tube is manufactured by using a hard-to-work material the chromium content of which is ≥4.5 mass%.

In the manufacturing method, the seamless tube is manufactured by Mannesmann tube making process using a hard-to-work peeled base stock the chromium content of which is ≥4.5 mass%. The base stock in the state where the average value when the largest value of the difference between the maximum value and the minimum value of the difference in level for the distance of 25 mm in the longitudinal direction of the base stock is measured at arbitrary ten points (ten-point average difference in level) is ≤2.0 mm is used. The, even when it is the had-to work material the chromium content of which is ≥4.5 mass%, by managing the difference in level after peeling, the occurrence of outside scabs and scalelike scabs is effectively suppressed.