An auxiliary insertion and removal device that is inserted into or removed from a lumen in a state where an inserting section of an endoscope having a longitudinal axis is inserted into and that aids insertion and removal of the inserting section into or from the lumen, the auxiliary insertion and removal device comprising: a tubular main body section that allows the inserting section to be inserted therein and is rotatable around the longitudinal axis, the tubular main body section including an inner tube, a reticular tube section having a tubular shape and an outer surface that is formed into a reticular pattern, and an outer tube that is arranged on an outer side of the reticular tube section and covers the reticular tube section; a fin section that is arranged on an outer peripheral surface of the main body section and spirally arranged in a predetermined direction to be wound around the longitudinal axis; a spiral tube section that is arranged on the main body section and arranged to be wound around the longitudinal axis in the same direction as the fin section or a direction opposite to the fin section; and a diameter change preventing section having the outer tube that is arranged in the main body section and that functions as an outer thick wall portion of the main body section, the diameter change preventing section being configured to prevent a diameter of the spiral tube section from expanding when the spiral tube section is wound in the same direction as the fin section and the main body section is rotated in the predetermined direction, or to prevent the diameter of the spiral tube section from contracting when the spiral tube section is wound in the direction opposite to the fin section and the main body section is rotated in the predetermined direction, wherein the inner tube of the main body section is arranged on an inner side of the spiral tube section and is covered by the spiral tube section, and the reticular tube section of the main body section is arranged on an outer side of the spiral tube section and covers the spiral tube section, characterized in that the diameter change preventing section has a diameter change preventing spiral tube section that is arranged on the outer side of the spiral tube section when the spiral tube section is wound in the same direction as the fin section, or is arranged on the inner side of the spiral tube section when the spiral tube section is wound in the direction opposite to the fin section, the diameter change preventing spiral tube section is arranged to be wound around the longitudinal axis in a direction opposite to the spiral tube section, and is sandwiched between the spiral tube section and the reticular tube section in the radial direction of the spiral tube section, and is bonded to the spiral tube section and to the outer tube through the reticular tube section. a tubular main body section that allows the inserting section to be inserted therein and is rotatable around the longitudinal axis, the tubular main body section including an inner tube, a reticular tube section having a tubular shape and an outer surface that is formed into a reticular pattern, and an outer tube that is arranged on an outer side of the reticular tube section and covers the reticular tube section; a fin section that is arranged on an outer peripheral surface of the main body section and spirally arranged in a predetermined direction to be wound around the longitudinal axis; a spiral tube section that is arranged on the main body section and arranged to be wound around the longitudinal axis in the same direction as the fin section or a direction opposite to the fin section; and a diameter change preventing section having the outer tube that is arranged in the main body section and that functions as an outer thick wall portion of the main body section, the diameter change preventing section being configured to prevent a diameter of the spiral tube section from expanding when the spiral tube section is wound in the same direction as the fin section and the main body section is rotated in the predetermined direction, or to prevent the diameter of the spiral tube section from contracting when the spiral tube section is wound in the direction opposite to the fin section and the main body section is rotated in the predetermined direction, wherein the inner tube of the main body section is arranged on an inner side of the spiral tube section and is covered by the spiral tube section, and the reticular tube section of the main body section is arranged on an outer side of the spiral tube section and covers the spiral tube section, characterized in that the diameter change preventing section has a diameter change preventing spiral tube section that is arranged on the outer side of the spiral tube section when the spiral tube section is wound in the same direction as the fin section, or is arranged on the inner side of the spiral tube section when the spiral tube section is wound in the direction opposite to the fin section, the diameter change preventing spiral tube section is arranged to be wound around the longitudinal axis in a direction opposite to the spiral tube section, and is sandwiched between the spiral tube section and the reticular tube section in the radial direction of the spiral tube section, and is bonded to the spiral tube section and to the outer tube through the reticular tube section.