Because the increased mental workload on nurses leads to worse patient outcomes, it is important to manage the mental workload of nurses properly. To respond to fluctuating conditions, workload management methods that can provide support in real-time are required. In recent years, research has been conducted on estimating techniques such as in ICUs, but the effects of using these techniques in real-time workload management have not been elucidated. Therefore, in this study, focusing on the mental workload in nursing teams, models that estimate mental workload and demand were used to examine the effectiveness of workload management by feedback on model estimation results. Specifically, through a simulation experiment in which five nurses provide care to patients in an ICU ward, data on the mental workload of each nurse is obtained when the system is used to present estimations of each nurse's workload and demands for care of patients after five minutes. From the results of the analysis of the acquired workload data, the feedback of the mental workload and the demand estimation results suggest effectiveness in reducing the workload of each individual and equalizing workloads within a team. It is considered that the use of a common tool within the team for assessing the situation of the team and the ward generated communication and led to the avoidance of workload imbalance.