PURPOSE: To set the protruding length of a protruding inner core with extremely high accuracy without generating irregularity by fixing the inner core to an inner pendulum and fitting the inner pendulum and an outer pendulum in a manner adjustable in the longitudinal direction thereof to constitute a completed pendulum and providing the completed pendulum in the writing part of a small pipe type writing utensil in a slidable manner.

CONSTITUTION: A metal inner core 2 is fitted to an inner core 2 is fitted to an inner pendulum 1 by chamfering processing applying force in the outer peripheral direction of the inner pnedulum l. The inner pendulum l is inserted in the inner hole 3A of an outer pendulum 3 made of a synthetic resin to fit the flat chamfered part IA of the inner pendulum l in the inner hole 3A of the outer pendulum 3 and the rear end part of the inner pendulum l is allowed to protrude rearwardly from the outer pendulum 3 in the longitudinal direction thereof and, at this temporary mounting point of time, the inner pendulum l is fitted in the outer pendulum 3 at the part appropriately rearward from a predetermined position in the longitudinal direction. The rear end of the inner pendulum l is pressed by the press jig 9 fixed to a motor and the point of time when the protruding quantity of the inner core 2 becomes predetermined length is detected on the basis of the leading end of a pen body 6 by a displacement sensor and the pressing of the inner pendulum l is released to constitute a completed pendulum.