An ultrasound endoscope according to the present invention includes: an insertion portion (10) configured to be inserted into a living body； a distal end rigid portion (10a) which is provided at a distal end of the insertion portion (10), includes an ultrasound transmitting and receiving unit (101), includes groove portions (102, 103) to which a balloon (106) surrounding the ultrasound transmitting and receiving unit (101) is mounted, and in which a balloon water supply port (104) configured to supply water to the balloon (106) is formed； a balloon water supply channel (128) communicating with the balloon water supply port (104)； a water supply pipe (124) which is provided in a universal cable (12) that connects the connector portion (13) connecting the ultrasound endoscope (2) to a light source device (6) and an operating unit (11)； an air supply and water supply cylinder (121) which is provided in the operating unit (11) and to which one end of the balloon water supply channel (128) and one end of the water supply pipe (124) are opened； and a duct (136) to inject water into an injection port (135) provided in the balloon water supply channel (128).
