An endoscope comprising: a four-color separation prism configured to separate light from an object into three primary colors of light and infrared light: and four image sensors configured for converting optical images of the separated three primary colors of light and an optical image of the separated infrared light into electrical signals; wherein the four-color separation prism includes an infrared separation prism , a blue-color separation prism , a red-color separation prism and a green-color separation prism assembled in a sequence from a light incidence side in the optical axial direction as a first prism , a second prism , a third prism and a fourth prism in the sequence, wherein each of the first, the second and the third prisms respectively has a light incident surface , a reflective surface facing the light incident surface, and a light emitting surface , and the fourth prism has a light incident surface and a light emitting surface facing its light incident surface, wherein the four image sensors comprise an infrared image sensor disposed to face the light emitting surface of the infrared separation prism, a blue color image sensor disposed to face the light emitting surface (221 c) of the blue color separation prism , a red color image sensor disposed to face the light emitting surface of the red color separation prism and a green color image sensor disposed to face the light emitting surface of the green color separation prism , characterized in that the light incident surface of the first prism and the light incident surface of the third prism are arranged relative each other to form a first angle, wherein the light incident surface of the first prism and the light incident surface of the fourth prism are arranged relative to each other to form a second angle, wherein the first angle is less than the second angle. a four-color separation prism configured to separate light from an object into three primary colors of light and infrared light: and four image sensors configured for converting optical images of the separated three primary colors of light and an optical image of the separated infrared light into electrical signals; wherein the four-color separation prism includes an infrared separation prism , a blue-color separation prism , a red-color separation prism and a green-color separation prism assembled in a sequence from a light incidence side in the optical axial direction as a first prism , a second prism , a third prism and a fourth prism in the sequence, wherein each of the first, the second and the third prisms respectively has a light incident surface , a reflective surface facing the light incident surface, and a light emitting surface , and the fourth prism has a light incident surface and a light emitting surface facing its light incident surface, wherein the four image sensors comprise an infrared image sensor disposed to face the light emitting surface of the infrared separation prism, a blue color image sensor disposed to face the light emitting surface (221 c) of the blue color separation prism , a red color image sensor disposed to face the light emitting surface of the red color separation prism and a green color image sensor disposed to face the light emitting surface of the green color separation prism , characterized in that the light incident surface of the first prism and the light incident surface of the third prism are arranged relative each other to form a first angle, wherein the light incident surface of the first prism and the light incident surface of the fourth prism are arranged relative to each other to form a second angle, wherein the first angle is less than the second angle. <EOS>