Abstract: An improved structure of a wheelchair includes a seat, a to-and-fro adjusting member, a left-and-right adjusting member, a bottom frame body, a wheel belt module, a vertical sensor, and a retractable leakage prevention cover, wherein the seat is provided with a driving-controlled rod mounted at one lateral side of the handrail of the wheelchair for the user to control in moving to-and-fro. The wheelchair is maintained at a horizontal position during the climbing up or moving down a bumpy road or a plurality of steps. Thus, a user sitting on the seat will keep comfortably in a horizontal position.