Patent ID: 8449127

Claim:
An endoscope objective lens comprising, in sequence from an object side: a front group; an aperture stop; and a back group, wherein the front group includes, in sequence from the object side, a negative first lens whose concave surface faces an image side and a positive second lens whose convex surface faces the object side and whose flat surface or concave surface is located on the image side, and a filter disposed between the first lens and the second lens, and the back group includes, in sequence from the object side, a positive third lens whose convex surface faces the image side, and a combined lens formed of a plano-convex lens or a biconvex lens and a negative meniscus lens, and the endoscope objective lens satisfies the following Conditional Expressions (1) and (2) n 3 >−v 3/12+5.5 (1) 2.0 >df/Ih> 1.5 (2) where n3 is the refractive index of the third lens, and v3 is the Abbe number of the third lens, df is the sum of the thickness of an optical element and the inter-surface distance from the apex of the concave surface of the first lens to the aperture stop, and Ih is the maximum image height.