<；P>；PROBLEM TO BE SOLVED: To provide a catheter which has a prolongation tool and allows a transmitting/receiving part to move inside a sheath, thereby to improve workability； and a prolongation tool for the catheter. <；P>；SOLUTION: The catheter includes a catheter body 2 inserted into a body cavity and a prolongation tool 3 which connects the catheter body 2 to an outer driving device 100 for driving the catheter body 2, wherein a transmitting/receiving part 41 mounted to the catheter body 2 can move along the axial direction of a sheath 20； and a driving shaft 42 connected to the transmitting/receiving part 41 and a signal path 54 can be connected to the outer driving device 100 through a prolongation shaft 60 mounted to the prolongation tool 3 to be movable along the axial direction and a prolongation signal path 64. <；P>；COPYRIGHT: (C)2011,JPO&INPIT
