An insertion portion rigidity changeable catheter with a balloon has an insertion portion including a coil-shaped member which is extensible and contractible and has a predetermined elastic force, with a compression length set to be a predetermined length, and a sheath which is a tube body with predetermined flexibility having a fluid conduit, includes a sheath main body surrounded by the coil-shaped member, and a sheath end portion provided at one end side of the sheath main body, having a diameter larger than the sheath main body and having a contact surface which one end surface of the coil-shaped member contacts, has one opening of the fluid conduit in the sheath end portion and has another opening of the fluid conduit at another end side of the sheath main body, an inflatable/deflatable balloon which is provided at the sheath end portion of the sheath, and is configured to be inflated by being supplied with a fluid via the one opening of the fluid conduit to expand an outside diameter dimension to be a diameter larger than an outside diameter of the sheath end portion, and to be deflated by the fluid being discharged via the one opening to be brought into close contact with an outer circumferential face of the sheath end portion, and an operation section which is fixedly provided at another end side of the sheath, and includes an operation section main body including a fluid supply and discharge apparatus connection portion which is directly or indirectly connected to a fluid supply and discharge apparatus which performs supply of the fluid into the balloon via the fluid conduit, or discharge of the fluid in the balloon, and a slide member which is slidably disposed in an inner surface side of the operation section main body, and is disposed at another end side of the operation section main body by an elastic force of the coil-shaped member.
