An electronic endoscope has a light source configured to emit normal light toward an object and a rotating filter configured to be positioned in the path of light that passes from the light source to an image sensor. The rotating filter has an optical band-pass filter and a ND filter. The electronic endoscope has further a rotation controller that synchronizes a light-path traverse-interval of the band-pass filter and a light-path traverse-interval of the ND filter with a field/frame interval and an image generator that generates a normal image from broadband image-pixel signals and generates a spectral image from specific-band image-pixel signals. The image generator has a brightness adjuster that increases a brightness level of the spectral image. Then, the ND filter reduces an amount of light emitted from the light source to an amount of light that corresponds to an increased brightness of the spectral image.
