PROBLEM TO BE SOLVED: To provide an extra-fine endoscope capable of easily changing a course in an intended direction, and to provide an endoscope apparatus, and an endoscope system.SOLUTION: An insertion section 7 of an endoscope includes a distal end hard section 19, a bent section 20, and a flexible tube 21. An observation optical system 22 and an image guide 23 are stored in the distal end hard section 19. The bent section 20 includes a rotation tube 36, a protrusion part 37, and a support member 38. A rotation mechanism for rotating the rotation tube 36 has a support member 38 and an endless wire 40. The endless wire 40 is wound around a second outer peripheral face 36b of the rotation tube 36. When the rotation tube 36 of the insertion section 7 is extracted from a distal end tube part 49 of a guide sheath 4, the protrusion part 37 presses a flexible tube 21 and the rotation tube 36 is bent along with the flexible tube 21. When the endless wire 40 is pulled and the rotation tube 36 rotates, the protrusion part 37 rotates to vary the direction where the rotation tube 36 bends.
