A microscope objective lens comprising, in order from the object side: a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power, wherein the first lens group includes a positive lens component having a lens surface positioned nearest to the object side and having a negative refractive power and at least one cemented lens component having a combined positive refractive power, the second lens group includes a diffractive optical element that joins two diffractive element components and respectively made from different optical materials and which has a diffractive optical surface on which diffractive grating grooves are formed on the bonded surface of the two diffractive element components, and at least one cemented lens component, the third lens group includes at least one achromatic lens component having a combined negative refractive power, and a lens surface of the third lens group nearest to the image side is arranged so that a concave surface of the lens surface faces the image side, the microscope objective lens configured such that if r denotes a curvature radius of the surface having a negative refractive power of the positive lens component provided in the first lens group, n1 denotes a refractive index of an object-side medium of the surface having a negative refractive power with respect to the d line, n2 denotes a refractive index of an image-side medium with respect to the d line, and d0 denotes a distance on an optical axis from a vertex of the surface having a negative refractive power to the object, then the microscope objective lens satisfies a condition expressed by | n 2 − n 1 / r ⋅ d 0 | < 0.01 mm − 2, and if f denotes a focal length of the entire system and h denotes a height from an optical axis of a principal ray of a light bundle passing through the diffractive optical surface and corresponding to a maximum field angle, then the microscope objective lens satisfies a condition expressed by 0.05 < | h / f |. a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power, wherein the first lens group includes a positive lens component having a lens surface positioned nearest to the object side and having a negative refractive power and at least one cemented lens component having a combined positive refractive power, the second lens group includes a diffractive optical element that joins two diffractive element components and respectively made from different optical materials and which has a diffractive optical surface on which diffractive grating grooves are formed on the bonded surface of the two diffractive element components, and at least one cemented lens component, the third lens group includes at least one achromatic lens component having a combined negative refractive power, and a lens surface of the third lens group nearest to the image side is arranged so that a concave surface of the lens surface faces the image side, the microscope objective lens configured such that if r denotes a curvature radius of the surface having a negative refractive power of the positive lens component provided in the first lens group, n1 denotes a refractive index of an object-side medium of the surface having a negative refractive power with respect to the d line, n2 denotes a refractive index of an image-side medium with respect to the d line, and d0 denotes a distance on an optical axis from a vertex of the surface having a negative refractive power to the object, then the microscope objective lens satisfies a condition expressed by | n 2 − n 1 / r ⋅ d 0 | < 0.01 mm − 2, and if f denotes a focal length of the entire system and h denotes a height from an optical axis of a principal ray of a light bundle passing through the diffractive optical surface and corresponding to a maximum field angle, then the microscope objective lens satisfies a condition expressed by 0.05 < | h / f |.