In the present analysis study, an analysis model was developed using ANSYS Workbench to verify the dynamic characteristics of the cabinet and the vibration reduction effect of applying TMD. The analysis modeled a simplified equivalent structure of a nuclear power plant cabinet, and a method was explored to reduce the cabinet's resonant response by installing TMD on top of the cabinet. For the analysis, harmonic loads and SSE seismic waves were input to conduct modal analyses of the cabinet and TMD. The cabinet vibration reduction effect of TMD installation was investigated, as well as the time histories of displacement and acceleration. The analysis results showed that the primary mode of the cabinet had a MPMR of approximately 53.9%, significantly affecting the dynamic behavior of the cabinet compared to other modes. However, a MPMR of approximately 8.9% was also observed in higher-order modes. With TMD installed, the peak response was significantly reduced, the larger curve split into two smaller curves, and the response at the original natural frequency was reduced by up to approximately 60%. The cabinet's time response showed a decrease in displacement/acceleration vibration response as the damping ratio increased. This indicates a narrow bandwidth and peak suppression of the response envelope, and the maximum displacement and acceleration reduction effects were approximately 33.1% and 27%, respectively.