An insertion apparatus (10) for an endoscope includes a tubular body (20) which is inserted into a surgical tool insertion channel (92) of the endoscope, and a wire member (30) which is inserted into an inside cavity of the tubular body. The tubular body includes a distal end coil (22) which is provided in the distal end side of the tubular body, a proximal end coil (24) which is provided at the proximal end of the distal end coil, and has an inside diameter smaller than an inside diameter of the distal end coil, and an inside diameter changed member (23) which is provided between the proximal end of the distal end coil and the distal end of the proximal end coil, and changed in the inside diameter to connect the proximal end of the distal end coil and the distal end of the proximal end coil.
