A differential interference contrast
microscope including an illuminating
light source, a
polarizer for converting an illumination light
ray into a
linearly polarized light, a polarized light separating unit for dividing the
linearly polarized light ray into two
linearly polarized light rays having mutually orthogonal vibrating directions, an illuminating optical
system, for projecting the two linearly polarized light rays onto an object under inspection, a polarized light combining unit for combining the two linearly polarized light rays on a same
optical path via an inspecting optical
system, an analyzer for forming a differential interference contrast image on an imaging plane. The polarized light separating unit is constructed such that an amount of
wavefront shear between the two linearly polarized light rays on the object can be changed, and the polarized light combining unit is arranged between the object and the analyzer at such a position that the two linearly polarized light rays propagate in parallel with each other and is constructed such that the two linearly polarized light rays can be combined with each other in accordance with the shear amount of
wavefront introduced by the polarized light separating unit.