Endoscope optical system, endoscope objective lens, and endoscope

The utility model relates to an endoscope optical system, an endoscope objective lens and an endoscope. The endoscope optical system sequentially comprises a first lens group with negative focal power, a diaphragm and a second lens group with positive focal power from an object side to an image side along an optical axis, and the first lens group sequentially comprises a first lens with negative focal power and a second lens with positive focal power from the object side to the image side along the optical axis. The second lens group sequentially comprises a third lens with positive focal power, a fourth lens with positive focal power and a fifth lens with negative focal power from the object side to the image side along the optical axis; the endoscope optical system satisfies 1.7 < = LG1/f < = 1.9. According to the endoscope optical system, the requirement of miniaturization design can be met, and therefore damage of an endoscope to a patient can be reduced to the maximum extent. 本实用新型涉及一种内窥镜光学系统、内窥镜物镜及内窥镜。内