Patent ID: 8142348

Claim:
An endoscope insertion apparatus for inserting an endoscope into a duct, the endoscope insertion apparatus comprising: inner-side arm members that press a duct wall; an inner-side insertion assisting section in which the inner-side arm members are uniformly arranged in a circumferential direction on a distal end side of an inner-side insertion assisting section body portion; outer-side arm members that press the duct wall; and an outer-side insertion assisting section mounted on an outer circumferential portion of the inner-side insertion assisting section, in which the outer-side arm members are uniformly arranged in a circumferential direction on a distal end side of an outer-side insertion assisting section body portion such that the inner-side arm members and the outer-side arm members are alternately arranged circumferentially around the outer-side insertion assisting section; wherein the inner-side arm members can be changed between a reduced diameter state and an expanded diameter state in which the inner-side arm members press the duct wall, and the outer-side arm members can be changed between a reduced diameter state and an expanded diameter state in which the outer-side arm members press the duct wall, and the outer-side arm members and the inner-side arm members move forward and rearward with respect to each other in an insertion direction such that the outer-side arm members and the inner-side arm members alternately change between: a state in which the outer-side arm members in the expanded diameter state change to the reduced diameter state and the inner-side arm members in the reduced diameter state change to the expanded diameter state, to thereby change a front/rear relationship with respect to the insertion direction between the outer-side arm members and the inner-side arm members; and a state in which the inner-side arm members in the expanded diameter state change to the reduced diameter state and the outer-side arm members in the reduced diameter state change to the expanded diameter state, to thereby change a front/rear relationship with respect to the insertion direction between the inner-side arm members and the outer-side arm members.