An interferometric measuring device for measuring a measured object, in particular for thickness measurement of the measured object. A special-purpose objective having a mirror system is provided, which includes at least one first deflection mirror and one second deflection mirror and in which these are situated in such a way that the object beams incident on the first deflection mirror or on the second deflection mirror are directed respectively onto a first side or a second side, which is parallel thereto, of the measured object to be measured in a first beam path or a second beam path, respectively, which are antiparallel to one another. The mirror system additionally has at least one first position mirror for imaging the position of the measured object to be measured in relation to the first deflection mirror and/or the second deflection mirror.