An inner tube includes a tubular body made of a first resin and a reinforcing member disposed on an inner side of the tubular body. The reinforcing member is configured of a linear body including a second resin. The inner tube has a first region including a distal portion provided with a distal opening portion and a second region that is disposed to be closer to a proximal side than the first region. The linear body projects inwardly from the inner surface of the tubular body in the first and second regions, and inwardly projects less in the first region than in the second region. In a balloon catheter, guide wire operability is improved and problems which can arise when using a metal reinforcing member are avoided. In a medical elongated body, sliding resistance of a medical device inserted in a lumen can be reduced.