Abstract: An anti-fogging lens device, having a plural number of optical glass lens elements mounted within a lens barrel, including a first lens element located in a foremost position on the side of a subject and a second lens element located behind and at a space from the first lens element. A spacer ring is fitted in the lens barrel to set apart the first and second lens elements by a gap space of a predetermined width. The spacer ring is formed of a material having higher thermal conductivity than the lens elements and, on the inner peripheral side thereof, provided with a moisture depositing surface which is formed in a non-flat shape to increase its surface area. The lens barrel is fitted in a cylindrical member, and a seal pocket, to be packed with a seal material, is formed between the lens barrel and the cylindrical member to stop clearances between these two members with a secure hermetical seal.