A medical treatment tool (1) includes: an insert portion (3) at least a part of which is provided by a flexing portion (32) that is adapted to be flexed, the insert portion (3) being adapted to be inserted into a human body of a patient and an inflatable body (5) provided on an outer circumference of the flexing portion (32), the inflatable body (5) being inflated in a radial direction of the flexing portion (32). An axial distal end portion (51) of the inflatable body (5) is fixed to the insert portion (3) while a proximal end portion (52) of the inflatable body (5) is axially movable relative to the insert portion (3).
