An ultrasound endoscope capable of obtaining a favorable elastography image by a simple configuration without upsizing a distal end portion is provided. For this purpose, an ultrasound endoscope 2 is configured having an ultrasound probe 17 arranged at a distal end rigid portion 10, an auxiliary water feeding channel opening 24 through which fluid is ejected from a vicinity of the ultrasound probe 17 in a projecting direction of the ultrasound probe 17, an auxiliary water feeding channel 47 communicating with the auxiliary water feeding channel opening 24, and an adjustment valve 48 for variably adjusting a flow rate of the fluid flowing through the auxiliary water feeding channel 47 among two or more states.
