Abstract: The invention concerns a device for varying the valve timing of gas exchange valves of an internal combustion engine, said device being arranged in the region of the cylinder head (1) of the internal combustion engine on a camshaft (3) and comprising an element (6) which is attached to a crankshaft of the internal combustion engine and is in driving relationship with the crankshaft through a traction element, said device further comprising an element (7) attached rotationally fast to the camshaft (3), both of said elements (6, 7) being adapted to rotate and to be fixed relative to each other between two end positions in response to an adjusting element which is hydraulically actuatable by a solenoid control valve (25).