To provide a microscope objective lens which has a large numerical aperture and in which the flatness of an image surface is sufficiently corrected.

The microscope objective lens comprises, in order from an object side: a first lens group having positive refractive power as a whole; and a second lens group comprising, in order from the object side, a first gauss lens group, a lens group having positive refractive power and a second gauss lens group. When a distance from the object surface to the final lens surface of the objective lens is denoted as D and the entire focal length of the objective lens is denoted as F, the microscope objective lens satisfies a conditional expression: 3≤D/F≤35.