For providing an, ultrasound endoscope capable of obtaining a favorable elastography image by a simple configuration without upsizing a distal end portion, an ultrasound endoscope is configured having an ultrasound probe arranged at a distal end rigid portion, an auxiliary water feeding channel opening through which fluid is ejected from a vicinity of the ultrasound probe in a projecting direction of the ultrasound probe, an auxiliary water feeding channel communicating with the auxiliary water feeding channel opening, and an adjustment valve for variably adjusting a flow rate of the fluid flowing through the auxiliary water feeding channel among two or more states.
