PROBLEM TO BE SOLVED: To provide an image diagnosis catheter that has flexibility on the tip side and high rigidity on the base end side while preventing the enlargement of an outer diameter of a sheath.SOLUTION: An image diagnosis catheter 100 includes a rotatable driving shaft 140 provided with an ultrasonic transducer 145a at the tip, a sheath 110 into which the driving shaft is inserted, and which extends in an axial direction, and a rigidity changing part 10 disposed inside the sheath for making the rigidity of the driving shaft higher on the base end side than on the tip side.SELECTED DRAWING: Figure 3【課題】シースの外径の拡大を防止しつつ、先端側では柔軟性を備え、基端側では高剛性を備える画像診断用カテーテルを提供する。【解決手段】画像診断用カテーテル１００は、先端部に超音波振動子１４５ａが設けられた回転可能な駆動シャフト１４０と、駆動シャフトが挿入され軸方向に延在するシース１１０と、シースの内部に設けられ、駆動シャフトの剛性を先端側より基端側において高くする剛性変化部１０と、を有する。【選択図】図３
