There is provided an ultrasound endoscope of which a distal-end-part body of an insertion unit can be reduced in size.In an ultrasound endoscope according to an embodiment of the invention, a straight pipe portion of a first three-way pipe and a straight pipe portion of a second three-way pipe are arranged adjacent to each other in a direction orthogonal to the direction of a longitudinal axis of an insertion unit, and a branch pipe portion and the straight pipe portion are arranged at positions overlapping with each other in a case where the first three-way pipe and the second three-way pipe are projected onto a plane perpendicular to the direction of the longitudinal axis.
