A flexible tube insertion apparatus includes an insertion section, a stiffness variable unit that changes a bending stiffness of the insertion section and a detection unit that detects an advance that is a movement toward a distal end of the insertion section and a retreat that is a movement toward a proximal end of the insertion section. A controller controls the stiffness variable unit to change the bending stiffness of the insertion section to a first bending stiffness when the detection unit has detected the advance of the insertion section, and that controls the stiffness variable unit to change the bending stiffness of the insertion section to a second bending stiffness higher than the first bending when the detection unit has detected the retreat of the insertion section.
