The type of work involving humans and collaborative robots is gradually evolving into a form where they share the workspace and target products together. Consequently, the direct impact of robotic actions on humans has increased, necessitating a different perspective to analyze factors affecting the mental and physical stress burden on workers. This study assumes that changes in work speed and human personality should be considered when planning tasks and conducts experiments to understand how these two factors influence mental and physical stress. Participants were divided into two groups, each experiencing opposite changes in work speed, and stress data were collected through pre- and post-task surveys in an environment similar to a production line with collaborative robots. Both groups reported higher stress levels with rapid changes in work speed. Analyzing the collected data based on personality types revealed that groups with stress-vulnerable personalities experienced significantly more mental stress when work speed changed rapidly compared to other groups. Therefore, analyzing workers’ personalities using a simple questionnaire in advance and considering this along with speed changes in task planning can reduce overall stress, potentially leading to lower defect rates and increased productivity. Related Topic: CSCI-RTHI.