Abstract: The inventive nib body for marking pen is a polygonally prismatic rod-like body made of a porous and rigid material suitable for penetration of the marking ink. Each of the ridge lines formed between the polygonal, e.g. triangular or quadrilateral, end surface and the side surfaces serves as the line-drawing edge so that, when each of the edges has a different length from the others, lines of different widths can be drawn with different line-drawing edges by use of a single nib. Further, the line-drawing edge can be provided with one or more of notches and divided into sections so that the edge can be used for drawing, for example, a double-track line composed of two parallel lines.