The protective sheath front end of the disclosed curved section protective sheath for covering the curved section of an endoscope covers the outer periphery of the front end of the endoscope. A filamentous member is wound around the outer periphery of the protective sheath front end, affixing the protective sheath front end to the front end of the endoscope. An adhesive agent is layered on the outer periphery of the protective sheath front end so as to cover the filamentous member. A ring member is fitted to the protective sheath front end so as to cover the adhesive agent. The inner surface of the ring member is bonded to the filamentous member with the adhesive agent therebetween.