The invention provides a slip stopper which achieves a great slip stopping effect, and can be used for a location where a problem occurs if a through hole is opened therein. In a protruding portion that protrudes from the upper surface of a steel plate in the plate thickness direction, a concave portion and drain channels, that lead to the steel plate upper surface from the concave portion, are formed. The inner surface of the concave portion and the groove side surfaces of drain channels are formed by shear planes which extend substantially perpendicular to the steel plate upper surface, and are obtained by half blanking that does not open a through hole in the steel plate.