To provide an interference device which measures the surface profile of a surface to be examined and the homogeneity of an object or the like, with high precision.

The interference device comprises an optical means, which forms a light flux to be examined via an object to be examined and a reference light flux via a reference surface from a light flux emitted from a light source means, and combines both, to form an interference wavefront; a means of changing optical path length difference which changes the optical path length difference between the light flux to be examined and the reference light flux; an imaging device which images interference fringes based on the interference wavefront; and a processing unit which calculates the phase difference distribution of the interference wavefront from the interference fringes imaged by the imaging device. The interference device further comprises a correction means which corrects the phase difference distribution with a correction value, obtained by using a value obtained by a profile measuring device which mechanically measures the irregularities profile of the surface to be measured of a sample for correction and a value obtained, by measuring the sample for correction by using the interference device.

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