Provided is an endoscope which is capable of preventing liquid drops from attaching onto the vicinity of an observation window even in the case where the observation window is placed in the vicinity of a round-chamfered peripheral edge part. In the case where an observation window is placed in the vicinity of a round-chamfered peripheral edge part, the peripheral edge part in the vicinity of the observation window is round-chamfered in a manner that the radius of curvature (round-chamfer) becomes larger along with an increase in distance from a starting point, the starting point being the point closest to the observation window. With this feature, it is possible to prevent the liquid drops from attaching onto the vicinity of the observation window to thereby block the field of view.