A viewfinder device includes a first prism unit and a second prism unit. The first prism unit includes an incident/reflecting surface 1-1 for receiving and allowing light from the objective lens to enter the first prism unit, a surface 1-2 for reflecting the light entering from the surface 1-1, and a surface 1-3 for reflecting the light reflected by the surface 1-2. The second prism unit includes an incident/reflecting surface 2-1 for receiving and allowing the light reflected by the surface 1-3 to enter the second prism, a surface 2-2 for reflecting the light entering the surface 2-1, and a surface 2-3 for reflecting the light reflected by the surface 2-2. The surface 2-1 reflects the light reflected by the surface 2-3, and the objective lens forms an image between the first prism unit and the second prism unit.