An endoscope apparatus comprises: an endoscope including an insertion section； a cylindrical insertion assisting tool that allows the insertion section to be inserted to assist insertion of the insertion section into a body cavity； and a ring-shaped seal member that is supported so as to slide on the insertion section with the insertion section inserted, wherein the seal member is detachably mounted on a base end of the insertion assisting tool to seal a gap between the insertion assisting tool and the insertion section.
