A method for observing the branch portion of the hole comprising, a step of pushing an obstacle in the hole with an elbow portion； a step of rotating a guide member around an axial direction so that a distal portion of the guide member faces the branch portion extending laterally to an extending direction of the hole； a step of projecting an endoscope from the distal portion and inserting into the branch portion, while confirming an image； and a step of rotating the image to match an up-and-down direction of the image recognized by a user with an up-and-down of a vertical direction, after the endoscope is inserted into the branch portion.
