An endoscope comprising: an insertion portion that has a bendable portion including plural bending pieces connected with each other; and a bending manipulating device (22, 23) configured to bend the bendable portion by advancing and retreating a traction member (21a, 21b) extending from the bendable portion and including a manipulating lever being operated by an operator, a rotating member rotating with the traction member (21a, 21b) engaged, a driving motor configured to rotate the rotating member, and a speed reduction mechanism configured to transmit the driving force of the driving motor to the rotating member, characterized in that the speed reduction mechanism includes a sun gear rotated by the driving force of the motor and having first external teeth, plural planetary gears each having second external teeth engaging with the first external teeth of the sun gear, a first fixed gear having first internal teeth engaging with the second external teeth of the plural planetary gears, and a second movable gear having second internal teeth engaging with the second external teeth of the plural planetary gears, the number of second internal teeth being different from the number of first internal teeth, wherein the first gear is rotatably disposed and the speed reduction mechanism further comprises a switching mechanism configured to properly switch the first gear from a fixed state where the rotation of the first gear is stopped, to a movable state where the first gear is rotated when the manipulating lever is operated by the operator in conjunction with an operation of the driving motor, thereby the first gear starts to rotate and the rotation of the rotatable second gear is stopped while the planetary gears continue to rotate and revolve, and the bending of the bendable portion is stopped. an insertion portion that has a bendable portion including plural bending pieces connected with each other; and a bending manipulating device (22, 23) configured to bend the bendable portion by advancing and retreating a traction member (21a, 21b) extending from the bendable portion and including a manipulating lever being operated by an operator, a rotating member rotating with the traction member (21a, 21b) engaged, a driving motor configured to rotate the rotating member, and a speed reduction mechanism configured to transmit the driving force of the driving motor to the rotating member, characterized in that the speed reduction mechanism includes a sun gear rotated by the driving force of the motor and having first external teeth, plural planetary gears each having second external teeth engaging with the first external teeth of the sun gear, a first fixed gear having first internal teeth engaging with the second external teeth of the plural planetary gears, and a second movable gear having second internal teeth engaging with the second external teeth of the plural planetary gears, the number of second internal teeth being different from the number of first internal teeth, a manipulating lever being operated by an operator, a rotating member rotating with the traction member (21a, 21b) engaged, a driving motor configured to rotate the rotating member, and a speed reduction mechanism configured to transmit the driving force of the driving motor to the rotating member, characterized in that the speed reduction mechanism includes a sun gear rotated by the driving force of the motor and having first external teeth, plural planetary gears each having second external teeth engaging with the first external teeth of the sun gear, a first fixed gear having first internal teeth engaging with the second external teeth of the plural planetary gears, and a second movable gear having second internal teeth engaging with the second external teeth of the plural planetary gears, the number of second internal teeth being different from the number of first internal teeth, wherein the first gear is rotatably disposed and the speed reduction mechanism further comprises a switching mechanism configured to properly switch the first gear from a fixed state where the rotation of the first gear is stopped, to a movable state where the first gear is rotated when the manipulating lever is operated by the operator in conjunction with an operation of the driving motor, thereby the first gear starts to rotate and the rotation of the rotatable second gear is stopped while the planetary gears continue to rotate and revolve, and the bending of the bendable portion is stopped.