Residual stresses which are developed in injection molded parts affect dimensional accuracy and mechanical and thermal properties of the final products. To predict the residual stresses in injection molded parts, three stages of injection molding, i. e., filling, packing, and cooling, must be taken into consideration for the thermal and flow analyses. Flow field analysis during filling and postfilling has been carried out by using the control volume based FEM/FDM hybrid method. The generalized Hele Shaw flow is assumed. Compressibility of the polymer melt is calculated during packing and cooling stages. Modified Cross model is employed to reflect the dependency of the viscosity upon shear rate and temperature. An equation of state proposed by Tait offers efficient means to describe pvt-relationship of the polymer. Variation in temperature and pres-sure field is obtained over all stages through the flow analysis and used as input data for the solid state stress analysis of the part. Plane stress elements, such as shell elements, are used for finite element stress analysis of injection molded parts with appropriate boundary conditions both in the mold and after ejected from the mold. Numerical analysis yields useful informations which are relevant to the mechanical properties of solid state for the final products, e. g., residual stress distribution, shrinkage, displacement field, strain distribution, warpage, and weld line locations. Other results are also obtained; pressure field, temperature field, sink marks, and proper operating conditions.