An injection pen capable of saving labor by controlling the injection amount within a safe range is provided. An injection pen according to the present invention has a rotation propulsion device and a drug bottle case, and can be used with a drug bottle and an injection needle attached thereto. A tube, a spiral inner tube, a spiral propelling tube, a screwing ring, a propelling rod body, a reverse rotation preventing ring, and an injection operation member, and when injecting, the reverse rotation preventing ring of the push rod is a spiral propelling tube The rotation direction of the push rod and the spiral propulsion tube is restricted by contacting with the reverse rotation preventive annular tooth portion, and the propulsion rod body is also restricted by the assembly member and cannot be rotated. Since the piece is positioned in the groove portion of the spiral propulsion tube and the guide protrusion is positioned in the long groove, the spiral propulsion tube and the injection operation member are linearly propelled forward, and the guide convex portion of the spiral propulsion tube is the guide of the inner tube. Since it is screwed into the groove, the spiral inner tube rotates in the forward direction. When the spiral propelling tube is propelled forward, it becomes impossible to move backward due to the structure of the spiral groove and the spiral propelling tube of the outer spiral tube, so that the safety in using the injection pen can be improved. . [Selection] Figure 2【課題】特に注射量を安全範囲内に制御することにより省力化が可能な注射ペンを提供する。【解決手段】本発明に係る注射ペンは、回転推進装置及び薬剤瓶ケースを有し、薬剤瓶及び注射針を装着して使用することができ、該回転推進装置は、組立部材と、螺旋外管と、螺旋内管と、螺旋推進管と、螺合リングと、推進棒体と、逆回転防止リングと、注射操作部材を備え、注射する時、押し棒の逆回転防止リングを螺旋推進管の逆転防止環状歯部に当接させることにより、押し棒及び螺旋推進管の回転方向を制限し、推進棒体も組立部材により制限されて回転できなくなり、螺旋外管の軸方向逆移動防止弾性片が螺旋推進管の溝部に位置すると共に、案内突起が長溝に位置するので、螺旋推進管と注射操作部材が前方へ直線推進し、また、螺旋推進管のガイド凸部が螺旋内管のガイド溝に螺合されるので、螺旋内管が順方向に回転し、その螺旋推進管を前方へ推進させると、螺旋外管の螺旋状溝と螺旋推進管との構造により後退することが不可能となるため、注射ペンの使用上の安全性を向上させることができる。【選択図】図２
