We report on methodology for measuring residual stress of nano-meter thickness scale CVD film by using micro-cantilever deflection. In this methodology, cantilever pairs of bilayer and monolayer cantilevers were fabricated simultaneously. In order to coat film of interest only onto the top of the bilayer cantilever, it was deposited before cantilever releasing process. Also, protective PR layer was adopted to keep film of interest from high temperature and chemically reactive environments. Deflection difference between bilayer and monolayer cantilevers was transformed into residual stress of film by using Stoney’s equation. By using this method, we measured stress of PECVD SiNx of 20nm thickness and it was 282.22MPa on average with standard deviation of 48.61MPa.