An automatic flaw removing method for long materials, comprises the steps of: inspecting long materials, such as round-bar steels and steel pipes, for surface flaws by a flaw inspecting apparatus of all section to divide the long materials into rejected materials having a flaw(s) and accepted materials having no flaw; storing information on the longitudinal position and length of each of the flaws of the rejected materials in a storage unit; sequentially carrying out the tracking of each of the rejected materials; moving a circumferential flaw probe directly connected to a grinder, to a longitudinal coordinate position of each of the flaws of the rejected materials, on the basis of the information on the longitudinal position of each of the flaws stored in the storage unit, when each of the rejected materials arrives at a flaw grinding position; rotating each of the rejected materials; identifying a circumferential position of each of the flaws by picking up a flaw indicative signal by the circumferential flaw probe; and automatically grinding each of the rejected materials, on the basis of the information on the identified circumferential position of each of the flaws and the information on the longitudinal position and length of each of the flaws stored in the storage unit. Thus, it is possible to interlock a high-speed automatic flaw inspecting apparatus with an automatic grinder to automatically remove surface flaws of long materials.