Abstract: The object is to provide a writing instrument in which a large-diametric ink retaining portion with narrow grooves in width and still capable of securing a large enough air channel can be formed so that the replacement of the sufficient amount of air can be effected between the ink retaining portion and the outside air. To achieve this, in an ink retaining portion (12), a plurality of cutouts (32) are formed so that each cutout (32) is formed to a right angle direction with respect to a center line (16a) of the sheet element (16) with a length equal to or greater than half the radius (R) (A≧(R/2), B≧(R/2)) and that one end of the cutout (32) is extended to the periphery.