Thin films deposited by physical vapor deposition (PVD) were studied in terms of residual stress by the authors. The final purpose of our study is to evaluate the stress state at the interface between a substrate and a thin film. In this study, JIS-SKH55 tool steel without thin-film deposition was used as the specimen. SKH55 is a dual-phase steel consisting of martensite a’Fe and alloyed carbide M6C2. The specimens were heated to 573K, 798K, 843K and 893K. Recently, the relationship between the misfit of plastic strain and stress obtained by X-ray stress measurement has been proposed by the authors using the Eshelby/Mori-Tanaka model (EMT model). The residual stress and the misfit of plastic strain were determined by X-ray stress measurement using the EMT model. Results showed that as annealing temperature increased, the compressive residual stress remained nearly constant up to about 800K, and decreased above 800K in both phases. The misfit of plastic strain also remained nearly constant up to about 800K, and reached zero above 800K.