Abstract: An indexable milling insert comprising a polygonal shaped body having an upper surface, a lower surface and side surfaces. The upper surface includes a peripheral land intersecting the side surfaces has a predetermined width (a) sloping downward at a predetermined angle (X). A support-face plateaux extending from an end of the peripheral land up to a chip shaping surface has a predetermined angle. The angle (X) of the peripheral land is more positive than the angle (Y) of the support face plateaux.