In a composite writing instrument having mounted therein a plurality of writing devices including at least one ball-point pen refill equipped with a tip of the ball-point pen at a top end and an ink reservoir section at a rear end so that writing tip portions may be alternately allowed to project and retreat from an front body top, a pumping type pressurization mechanism is provided behind the ball-point pen refill, and a rear end of ink is pressurized by way of knock operation in a situation where a tip end portion has projected from a body end, so as to help the ink flow towards the tip side.