Problem to be solved: to provide a driving mechanism capable of restraining the occurrence of the rotation of the drive transmission member while suppressing the complication of the structure of the drive transmission member and ensuring that the drive transmission member and the driving portion can be reliably engaged.The driving mechanism 300 comprises a driving section 200 and an adapter 60 disposed between the driving section 200 and the surgical instrument.The adapter 60 includes a drive transmission member 62 for transmitting a driving force to the surgical instrument from the driving portion 200.The drive transmission member 62 has a first member 623 engaged with the surgical instrument and a second member 624 engaged with the driving portion 200.Further, the drive mechanism 300 has a friction torque T1 generated at the peripheral portion 623d which is a contact portion of the first member 623 with respect to the body portion 61 of the adapter 60 than the friction torque T2 generated at the end face 624e which is a contact portion of the second member 624 with respect to the drive part It is configured to be large.Diagram【課題】駆動伝達部材の構造が複雑化することを抑制しつつ、駆動伝達部材の連れ回りが発生することを抑制して、駆動伝達部材と駆動部とを確実に係合させることが可能な駆動機構を提供すること。【解決手段】この駆動機構３００は、駆動部２００と、駆動部２００と手術器具との間に配置されるアダプタ６０と、を備える。また、アダプタ６０は、駆動部２００から手術器具に駆動力を伝達する駆動伝達部材６２を含む。また、駆動伝達部材６２は、手術器具に係合する第１部材６２３と、駆動部２００に係合する第２部材６２４と、を有する。また、駆動機構３００は、アダプタ６０の本体部６１に対する第１部材６２３の接触部分である周縁部６２３ｄにおいて発生する摩擦トルクＴ１が、駆動部２００に対する第２部材６２４の接触部分である端面６２４ｅにおいて発生する摩擦トルクＴ２よりも大きくなるように構成されている。【選択図】図８
