A flexible tube insertion apparatus includes an insertion section, one or more stiffness variable portion, and a detection unit. The flexible tube insertion apparatus includes a bending information calculator, a main determiner, and a controller that performs control to increase a stiffness of the stiffness variable portion provided in a segment located in a bent part, when the main determiner determines that the bent part is present and the segment provided in the stiffness variable portion is located in the bent part.
