As the possibility of a chemical, biological and radiological (CBR) attack increases, the importance of CBR protective facilities has been emphasized. When CBR warfare emerges, people outside the CBR protective facility should come into the facility through a decontaminating process in a Contamination Control Area (CCA) and Toxic Free Area (TFA). If a bottleneck occurs in the entering process, it may take a long time to enter the facility, which may result in casualties. However, the current design criteria of the CBR protective facility is only limited to the shielding, ventilation and filtration system and it does not consider the long time it takes to enter the facility. Thus, this research aims to propose the bottleneck evaluation model for entering procedures in a CBR protective facility based on discrete event simulation. To develop the simulation model, the procedures performed through CCA and TFA are defined and segmented. The actual time of the procedures are measured and adapted for the simulation model. After running the simulation model, two elements causing bottlenecks are selected for alternatives with adjustments. According to the simulation results, the number of airlocks is the most important element that affects the bottlenecks and the delay time is greatly decreased when increasing the number of airlocks. Finally, three new articles to complement the existing criteria are proposed. The evaluation model is expected to help in the consideration of time during the designing phase of a CBR protective facility and to help CBR protective facility managers in planning the operation of a facility in a more realistic approach.