The present invention discloses a labor-saving pivotal shaft structure, comprising a fixed part and a movable part, wherein the movable part and the fixed part produce a frictional torque therebetween to provide the movable part with the functions of rotating, arresting, and positioning relative to the fixed part; and a torsion rod which is a rigid rod, whose one end is mounted onto the fixed part; such that the fixed part is connected to a main frame and the movable part as well as the other end of the torsion rod are respectively connected to a cover frame, and thus when the cover frame is being closed down, the fixed part is in a fixed condition and the torsion rod and the cover frame rotate together, leading to the torsion rod being in a twisted condition of storing energy; whereas when the cover frame is being opened up, the stored energy of the torsion rod is released to provide an auxiliary force.