Abstract: An arm rest device for relieving load when performing work by hand and wrist movements comprises an attachment member for mounting the arm rest on a chair; an upper support for supporting the forearm and arranged to be self-positioning while supporting the forearm and work being performed by hand and wrist movements, said support accompanying the hand and wrist movements; an adjustable horizontal guide rail attached to said upper support and movably disposed in longitudinal direction to provide a corresponding adjustment of said support due to the influence of a force generated when the hand is moved forwards or backwards; an adjustable vertical guide rail which is movable in its longitudinal direction to provide a corresponding adjustment of said support due to the influence of a force generated by the weight of the forearm and by external forces exerted on the forearm; and a joint of elastic material arranged below said horizontal guide rail, carrying said horizontal guide rail and said support, said elasti