Objective: This study investigated an effect of a level of physical workload on individual's ability of time perception. Background: Having a low discrepancy between a clock time and perceived time indicates a good health condition. While previous studies have found an effect of mental workload on perceived time, no study had yet revealed a relationship between physical workload and time perception. Method: Thirty participants evaluated to assess the subjective physical workload of four different tasks using Borg Category Rating 10. They were, then, asked a perceived time spent on each task to calculate a time perception ratio to a clock time. Heart rate was also measured before and after each task to calculated change in heart rate. Results: A level of subjective workload, measured by Borg Category Rating 10 (CR 10), was highly correlated with a change in heart rate. Using the two measures of physical workload, we found a strong correlation between a level of physical workload and change in time perception ratio. Also, a level of physical workload, in terms of a change in heart rate and Borg CR 10, could significantly predict a change in time perception ratio with 𝑅 value of 0.552 and 0.534, respectively. Conclusion: When participants performed a task with a higher level of physical workload, they tended to think that "time flew". Application: The result of this study can be applied to determine an appropriate amount of physical workload of a task to lower a discrepancy between a clock time and perceived time.