Stresses of main stop valve and control valve casings for the steam turbines of power plants are analyzed by the finite element method. The stress intensity is obtained to check the results on the basis of the design criteria of ASME boiler and pressure vessel code. To verify accuracy of the finite element analysis. analyzed stresses are compared with those measured during the hydrostatic pressure test. Stress category drawings. which play an important role in evaluating casting defects, are produced from the analysis results, and important points in casting of the valve casings are discussed in terms of the stress category.