Abstract: An ultrasound catheter capable of reducing noise in an ultrasound image by limiting reflection of ultrasound oscillated from a distal end side surface of a transducer. The ultrasound catheter includes: an elongated sheath; an ultrasound transducer; a shaft that supports the ultrasound transducer; and a cap that seals an opening portion of the sheath and has an X-ray opaque property. The cap includes an extension portion including a proximal portion facing the ultrasound transducer and an outer circumferential surface facing an inner circumferential surface of the sheath. The proximal portion includes an ultrasound scattering surface that scatters ultrasound from the ultrasound transducer. The outer circumferential surface includes a contact portion that is in contact with the inner circumferential surface of the sheath in a liquid-tight manner. The ultrasound scattering surface intersects with a virtual plane obtained by enlarging the ultrasound oscillation surface in an in-plane direction.