The disclosed technology is directed to an insertion assist system for an endoscope. The insertion assist system comprises a tube configured to control movement of an insertion portion of the endoscope during an advancing direction and a restrictor being disposed inside the tube and configured to restrict a protruding direction of the insertion portion. The tube includes an opening configured to receive the insertion portion to protrude therefrom. A guide surface is configured to control the advancing direction of the insertion portion and to restrict the protruding direction of the insertion portion. The restrictor is disposed facing the guide surface and is configured to press the insertion portion against the guide surface.
