RETRACTABLE WRITING INSTRUMENT

To prevent impairing of operativity of a holder caused by adhesion of a foreign matter.SOLUTION: A retractable writing instrument includes a mechanical pencil unit 1 which advances a holder 20 relative to a lead core x inserted to a holder 20 by a force component in a radial direction applied to the holder 20 projecting from the front end opening of a holding cylinder 10 and relative to the holding cylinder 10, and advances the mechanical pencil unit 1 with a predetermined operation and projects it from the front end opening of a shaft cylinder a1. The retractable writing instrument is provided with a large-diameter part 11a enlarging its diameter in a rear direction on a front end side of the outer periphery of the holding cylinder 10. The large-diameter part 11a is brought into slide contact with a pointed inner wall surface of the shaft cylinder a1 while advancing the mechanical pencil unit 1, and a contact part 11b between the holder 20 and the front end opening of the holding cylinder 10 secures a space s between the contact part and an inner wall surface of the shaft cylinder a1.SELECTED DRAWING: Figure 4 【課題】 異物の付着に起因してホルダーの動作性が損なわれるのを防ぐ。【解決手段】 保持筒１０の前端開口部から突出するホルダー２０に加わる径方向の力成分によりホルダー２０に挿通される鉛芯ｘ及び保持筒１０に相対しホルダー２０を前進させるシャープペンシルユニット１を備え、シャープペンシルユニット１を所定の操作により前進させて軸筒ａ１の前端開口から突出させるようにした出没式筆記具において、保持筒１０の外周前端側に後方向きに拡径する拡径部１１ａを設け、シャープペンシルユニット１の前進中に、拡径部１１ａを軸筒ａ１の先細状の内壁面に摺接させて、ホルダー２０と保持筒１０の前端開口部との接触部１１ｂが、軸筒ａ１の内壁面との間に隙間ｓを確保するようにした。【選択図】 図４