An intubation assistance instrument includes: an elongated assistance instrument main body to be inserted into a target site of a patient from a mouth cavity or a nasal cavity of the patient a guide member detachably attached to the assistance instrument main body, the guide member having a guide portion into which an intubation tube is to be inserted when the intubation tube is intubated into the target site of the patient, the guide portion capable of guiding the intubation tube to the target site and a lock mechanism that locks the guide member to the assistance instrument main body when the guide member is attached to the assistance instrument main body.
