Ultrasound endoscope and injection tool

An injection tool used in an ultrasound endoscope, the ultrasound endoscope comprising:

• an insertion portion configured to be inserted into a living body;
• an operating unit provided at a proximal end side of the insertion portion;
• an ultrasound transmitting and receiving unit provided at a distal end of the insertion portion and configured to transmit and receive ultrasound waves to and from the living body;
• a balloon surrounding the ultrasound transmitting and receiving unit;
• a balloon water supply channel provided in the insertion portion to supply water to the balloon;
• and a water supply cylinder which is provided at the operating unit and to which one end of the balloon water supply channel is opened, the injection tool comprising:
• a plug portion that is insertable into the water supply cylinder;
• a flow path provided in the plug portion and having one end to which a syringe for injecting or supplying fluid is attachable and having the other end through which the fluid injected or supplied from the syringe is configured to flow;
• and
• a lid portion configured to cover the water supply cylinder that is opened to outside the operating unit, and configured to allow the other end of the flow path to be positioned such that the other end of the flow path leads to the balloon water supply channel when the water supply cylinder is covered by the lid portion.