The rapid advancement of high-performance computing has significantly enhanced high frequency electromagnetic field analysis, contributing to shorter development cycles and lower costs for electronic devices. However, real-world medical environments involve complex geometries and large-scale domains that demand substantial computational resources. This study focuses on evaluating Electromagnetic Compatibility (EMC) within an operating room during the use of a microwave scalpel, which poses potential interference risks to other medical equipment. To address these challenges, we employ ADVENTURE_FullWave, a parallel finite element analysis system. The methodology is based on an edge element full-wave algorithm and an iterative domain decomposition-type parallelization method, which is effective for large-scale problems involving hundreds of millions of elements. This approach follows the established framework for predicting electromagnetic field distributions through stationary vector wave equations where the electric field is treated as an unknown function.[1] Leveraging the domain decomposition data structure is essential for modelling extensive analysis domains where mesh discretization typically 1/10 to 1/20 of the wavelength results in an enormous number of degrees of freedom. By leveraging the domain decomposition algorithm, the system achieves high parallel efficiency, enabling the robust processing of large-scale degrees of freedom on high-performance computing clusters. In this study, electromagnetic field analysis is performed at a frequency of 500MHz using a numerical model of an operating room that includes a human body model. By examining the electric field distribution, we successfully captured the complex interactions between the microwave energy and the surrounding environment. Specific details of these results and further findings will be presented at the conference. This research contributes to the improvement of electromagnetic environments in operating rooms and the overall safety and performance of medical devices.