An insertion apparatus includes: a flexible tube an electric driving source arranged on a proximal end side of the flexible tube a driven portion arranged on a distal end of the flexible tube and a single driving force transmitting member inserted in the flexible tube and formed by being wound in a coil shape. For the driving force transmitting member, first torsional rigidity in a first rotating state of being rotated in a direction of being wound in the coil shape is set higher than second torsional rigidity in a second rotating state of being rotated in an opposite direction and the driven portion performs a first motion by the first rotating state and performs a second motion requiring a larger amount of force than the first motion by the second rotating state.
