PROBLEM TO BE SOLVED: To prevent dirt from sticking to a duct for jetting or sucking a fluid and to easily strip off the dirt even if it sticks to the duct.SOLUTION: A distal end 16a of an insertion part of an endoscope includes an observation window 30 and an air/water feed nozzle 22. An air/water feed channel 21 is connected to the air/water feed nozzle 22. The air/water feed nozzle 22 jets wash water or air supplied from the air/water feed nozzle 21, to the observation window 30 to eliminate dirt sticking to the surface of the observation window 30. An inner wall surface 22d of the air/water feed nozzle 22 is provided with micro protrusions 40 at predetermined spaces to spread all over, thereby preventing the dirt from sticking to the inner wall surface 22d.
