PURPOSE: To solve the problem of cost reduction required for removing defective layer on the inner surface of a pipe and improve the yield of product.

CONSTITUTION: Annular second weir bodies 8, 9 for damming up molten metal and enabling a part of the molten metal to over flow are fitted at positions close to the center side of the mold 1 in the axial direction of the mold 1 distant from both weir bodies 5, 6 fitted to respective both end opening hole parts in the mold 1, respectively and the storing parts A1, A2 for storing the overflowed molten metal between the weir bodies 5, 6 are provided at both ends of the mold 1 and the second bodies 8, 9, respectively. Then, after the lapse of a fixed time from the point of time when casting the molten metal between both second weir bodies 8, 9 in the mold 1 during rotation, the rotating speed of the mold 1 is accelerated and a part of the molten metal overflows into both storing parts A1, A2 through both second weir bodies 8, 9.