Parallel and absolute measurement of surface shape using wavelength scanning interferometry are applied to various objects, including diffuse and milled surfaces having discontinuities such as steps, dips, and protrusions. We employ not only the Michelson setup but also the newly introduced Fizeau setup. The behaviors of interference signals arising from these objects are experimentally compared. Spiky noises are observed from the milled surfaces and from the defocused diffuse surface. In spite of the noise, we succeed in measuring steps and narrow dips on a mirror and a milled surface, as well as a cylindrical protrusion on a diffuse surface. With a dye laser of 4.2 nm tuning range we attain a resolution of 39 μm within a depth of 3 mm. © 2000 Society of Photo-Optical Instrumentation Engineers.