PROBLEM TO BE SOLVED: To provide an assistive device capable of performing a procedure difficult for a transnasal endoscope, and an endoscope system.SOLUTION: An assistive device 12 used in combination with a transnasal endoscope 11 that includes an insertion section 16 to be inserted from one external naris includes an insertion section 35 to be inserted from the other external naris. The insertion section 16 of the transnasal endoscope 11 and the insertion section 35 of the assistive device 12 include, at the tips thereof, magnets 23, 24, 40, and 41 as fixing means for closely fixing the tip ends in parallel such that the tip end faces face the same direction in an aligned state. The fixing and unfixing of the insertion sections 16 and 35 by the magnets 23, 24, 40, and 41 can be performed in the body cavity in which the insertion sections 16 and 35 are inserted.
