Expandable catheter

(57) It is a catheter (12) with the base end (20) which remains in the summary outside of the body, and the axial part (14) positioned inside of the body, and internal assistant てつ物 (26) is arranged inside of the body, and a predetermined part in the living body is treated, for example. The above-mentioned axial part (14) contains alternatively the component (18) which can expand in the end piece, and the component in which this expansion is possible, The component (18) which can expand to the posture of the expanded large section which expands the above-mentioned assistant てつ物 during the arrangement to the inside of the body from the posture of the small section which accommodates the above-mentioned internal assistant てつ物 (26) in the surroundings of the self in a compression form and which can expand alternatively, The resilient strip (30, 32) it was made to be expanded when it was spirally twisted around the surroundings of the above-mentioned component which can be expanded and the above-mentioned component which can be expanded was expanded to the posture of the above-mentioned large section is included.