ENDOSCOPE

PURPOSE:To avoid fogging and condensation on an observation window when an inserting part is inserted into a body cavity and observation is performed. CONSTITUTION:Four heat receiving fins 60 projecting outward in the radial direction are arranged on a lens cylinder 25 of an incident hole lens 22 set on an observation window of an insertion part 2 so as to shift the phase thereof each other by 90 deg. and an illuminating light projected from a light guide 24 is used as a heat source and this heat is transmitted to the incident hole lens 22 through the lens cylinder 25 from the heat receiving fins 60 to heat them incident hole lens 22. This heat receiving fins 60 are inserted in recessed parts formed on the projecting end face of the light guide 24 and are brought into contact with this projecting end face.