When we work seated for long periods of time, we do not sit in a completely fixed posture, but unconsciously change our posture as needed. This postural change is thought to instinctively reduce the physical fatigue caused by prolonged seating. Knowledge of this postural change strategy may pro-vide a guideline for maintaining a comfortable posture for extended periods of time. In this study, 16 healthy adult participants were asked to type on a desktop computer for 30 min and their musculoskeletal loads were estimated over time. The time-series changes of the estimated musculoskeletal loads during log-term sitting were analyzed. The results showed that the posture tended to be maintained by replacing the loads. In terms of load substitution, it was found that there were four patterns in which the balance of joint loads was changed and patterns in which joint loads were reduced, and muscle loads was increased. It was suggested that the posture was maintained while switching the load-applying part by changing the posture.