An ultrasound endoscope includes: an ultrasound probe arranged in a distal end rigid portion a suction and forceps port provided in a vicinity of the ultrasound probe a treatment instrument insertion channel and a negative pressure channel communicating with the suction and forceps port and a control valve configured to variably regulate a negative pressure for suction that is transmitted to the suction and forceps port through the treatment instrument insertion channel and the negative pressure channel to two or more states.
