PROBLEM TO BE SOLVED: To reduce the size of a movable shaft, which can be stably and accurately fed and moved. SOLUTION: A female threaded portion 84 is formed on an inner peripheral surface, a cylindrical body 70 rotatable around an axis and a male threaded portion 111 are formed on an outer peripheral surface, and a start position P1 and an end position are formed as the cylindrical body rotates. Power transmission for transmitting a driving force from the drive gear to the final gear via a movable shaft 71 movable between the two, a final gear 72 provided on the cylindrical body, a drive unit having a drive gear, and a plurality of intermediate gears. A mechanism 75 and a biasing mechanism 76 that applies a biasing force along the axial direction to the movable shaft, at least one of the plurality of intermediate gears is a two-stage gear 149, and the biasing mechanism has an end position. To provide a feeding device 4 that applies a biasing force toward the start position and presses the male screw portion to the start position side with respect to the female screw portion. [Selection diagram] Fig. 6【課題】可動軸を安定且つ精度良く送り移動させることができると共に、小型化を図ること。【解決手段】内周面に雌ねじ部８４が形成され、軸線回りに回転可能な筒体７０と、外周面に雄ねじ部１１１が形成され、筒体の回転に伴ってスタート位置Ｐ１とエンド位置との間を移動可能な可動軸７１と、筒体に設けられた最終ギア７２と、駆動ギアを有する駆動部と、複数の中間ギアを介して駆動ギアからの駆動力を最終ギアに伝える動力伝達機構７５と、可動軸に対して軸線方向に沿った付勢力を付与する付勢機構７６とを備え、複数の中間ギアの少なくとも１つは２段ギア１４９とされ、付勢機構は、エンド位置からスタート位置に向けて付勢力を付与し、雌ねじ部に対して雄ねじ部をスタート位置側に押し付ける送り装置４を提供する。【選択図】図６
