Centrifugal compressors employed in the oil and gas industry are operated at high gas pressure conditions and are used in a wide operation range. Accurate prediction of the rotating stall and the destabilizing aerodynamic force is one of the key technologies for these compressors. The aim of this study is to establish a method of accurately predicting the inception of rotating stall and its effect on shaft vibration. To achieve this, numerical investigations are carried out by unsteady flow and rotordynamic simulations. To validate the accuracy, an experiment is carried out at relatively high gas pressure conditions. In the first part of the study, the accuracy of compressor performance prediction is studied by steady computational fluid dynamics (CFD) simulation. It is found that by taking the wall roughness effect into account, the predicted performance shows good agreement with the experimental result. In the second part of the study, the accuracy of predicting the rotating stall is studied. In the experiment, two types of rotating stalls are measured. One is a multiple-cell stall induced in the vaneless diffuser and the other is a one-cell stall induced in the impeller. It is found that the simulation can predict the inception of the rotating stall with relatively high accuracy as the predicted results show good agreement with the experimental results in terms of cell count, rotation speed, pressure fluctuation level, and the effect on shaft vibration. Through this study, the effectiveness of simulation is validated for the stall and vibration prediction.