Vertical shaft pumps have relaticely low natural frequencies which are often very similar to the rotating frequency of rotor. If these natural frequencies interferes with the rotating frequency, high level resonance vibration developes which may damage the pump and make its operation impossible. Previous vibration analysis have been carried out using the analytical model consist of beam elements, however analytical results have been innacurate. The authors have applied component mode synthesis method to the vibration analysis of vertical shaft pump and confirmed that it proves satisfactory in actual practice with respect to accuracy. The authors have also developed pre- and post-processing programs specially designed for vertical shaft pump, with them the vibration analysis are performed in short period of time by anyone.