The workload factors for labor-intensive works of employees are always taken into account in measuring workloads. However, with the introduction of computers to work planning and coordination, the tasks have often begun to take on mental workload. Mental workload is encountered in academic studies in relatively high prevalence. In this regard, it is important to examine the efficiency of scientific studies to support the academic, administrative, and technical staff of a faculty. Many methods having certain disadvantages are available in the literature which is either conflicting or complementary to each other. Therefore, an integrated mental workload assessment method is needed. In this study, a new hierarchical method was proposed and by help of a scale developed, taking the subjective techniques (MCH, SWAT, NASA-TLX) into account, the faculty staff was holistically assessed in a fuzzy multi-criteria decision making processes. The subjects were selected in an engineering school at a private university. Four risk categories are defined that contain homogenous risk scores. At the end of the study, some ergonomic regulations are recommended to the persons/departments at high risk categories to reduce mental workloads.