An adjustment device for a cam-controlled valve operation in a piston-type internal combustion engine includes a camshaft adapted for actuating intake or exhaust valves of the piston-type internal combustion engine. The camshaft has a camshaft axis and includes an end having a guide surface. A transmission element constituting a magnetic armature is arranged for being moved back and forth in a direction of the camshaft axis. The transmission element includes an inner guide element opposite from and corresponding to the guide surface and a carrier element at a radial distance from the inner guide element that meshes with a corresponding carrier surface on a drive wheel, and is positioned for being twisted coaxially and relative to the camshaft. At least one of the guide surface on the camshaft and the carrier surface on the drive wheel is aligned in a helical shape relative to the camshaft axis. A stationary, switchable magnet has a pole surface facing the transmission element and presents a magnetic force that attracts the transmission element toward the pole surface when the magnet is switched on. A restoring mechanism is arranged along the camshaft and presents a force urging the transmission element away from the pole surface. A limit stop is disposed on the camshaft for holding the transmission element at a short distance from the pole surface of the magnet and counter to the force of the restoring means when the magnet is switched on.