To easily and surely perform replacement operation of a refill for a writing implement.

The opening part 4 of the body 2 of a refill vessel holding a refill 3 is closed or opened by the cover part 7 of an opening-closing body 6 which is axially fitted freely turnably around a supporting point 5. Then, the position of the opening degree of the opening-closing body 6 is suitably varied by retainment of both retaining projections 9 projected on the opening- closing body 6 and a plurality of retaining grooves 12 projected on a curved surface retaining body 10 integrally formed in the body 2 of the refill vessel and its state is held. Thereby, the opening-closing body 6 is turned in accordance with the amount of the refill 3 necessary for replacement operation and held in the position of the suitable opening degree. Therefor, a user easily and surely takes out only the necessary refill from the body 2 of the refill vessel. Furthermore, the opening part 4 of the body 2 of the refill vessel is surely closed excepting replacement operation and the refill 3 held in the inside thereof is prevented from being discharged to the outside.