A novel interferometric method, called a double shearing interferometry, is presented for profiling large-scale quasi-planar surfaces, such as semiconductor wafers, optical flats and x-ray mirrors. The surface profile is measured even under existence of the inclination of a scanning stage. By adopting the common-path optical configuration and the heterodyne detection, the proposed method realizes excellent resolution in sub-nanometer order and enables a robust measurement against unwanted disturbances due to the measurement environments. A height resolution of 0.1nm was experimentally achieved. A standard deviation of the analytical surface profiles was found to be 1.3nm, even when using a conventional screw-lead scanning stage. The measured results show that the surface profile and stage inclination are separately determined.We confirmed resultant profile was well consistent with the one measured with Fizeau interferometer.