An insertion assist system includes an insertion instrument and an assist instrument. The insertion instrument includes an elongated member, a first engagement portion provided in the elongated member, and a rigid portion provided on a distal side of the elongated member and having an appropriate length. The assist instrument includes a guide path that includes a bent section, at least apart of the bent section being bent, and that is configured to guide the rigid portion of the insertion instrument to a desired position on a distal side from the distal section, and a second engagement portion that is provided in the guide path and engaged with the first engagement portion of the insertion instrument, and that maintains the elongated member and the guide path in a contact or close state.
