Abstract: A binocular-type optical device for night as well as day vision. A night vision optical device is located in a central body. The night vision optical device includes an optical path which is folded through a pair of opposed holes in a central body containing the night vision device. Two lateral bodies are affixed to the central body, each lateral body having a hole facing the holes in the central body. One of the lateral bodies faces an oblong hole in the central body, and is rotatable with respect to the central body. Each of the lateral bodies includes a day vision optical system having an objective at one end and an eyepiece at another end. A mirror contained in each lateral body are adjustable to permit either the folded night vision optical path or the day vision optical path to be received by a pair of common eyepieces.