1. An endoscope comprising a slender insertion portion having a distal end and a proximal end; and a distal end face disposed at the distal end of the insertion portion, where an observation portion for observing an area to be examined and an illumination portion emitting illumination light are disposed on the distal end face, wherein the observation portion has an observation window on which an observation image of the area to be examined is incident, and at least a distal end observation face of the observation window is disposed at a position projecting to a distal end side of the insertion portion beyond the distal end face, wherein the distal end face includes at least a first face, which is a flat base face, a second face, which is a flat face, disposed at a portion projecting to a distal end side of the insertion portion beyond the first face, a third face, which is a flat face, disposed at a portion projecting to the distal end side of the insertion portion beyond the second face, and a fluid guide face disposed between the first face and the second face and is an inclination face inclined from the first face toward the second face, the observation portion and the illumination portion are disposed on the second face and the third face, the distal end observation face of the observation window disposed on the third face is disposed so as to project to the distal end side beyond the third face, the first face, the second face and the third face are configured to be externally exposed when the endoscope is used, the first face has a gas-feeding/water-feeding nozzle, the fluid guide face is disposed between the gas-feeding/water-feeding nozzle and the observation portion disposed on the second face in a plan direction of the distal end face, the gas-feeding/water-feeding nozzle has a jetting port opening toward the fluid guide face and the observation portion disposed on the second face, the second face projects to the distal end side of the insertion portion beyond the jetting port, and the third face projects to the distal end side of the insertion portion beyond the gas-feeding nozzle.