A electromagnetic camshaft adjuster comprising: an armature unit which can be moved relative to a pole core when a stationary coil unit is energized and which has an armature plunger; and a permanent magnet unit by means of which the armature unit is held in a rest position when the coil unit is not energized; and a spring element between the pole core and the armature unit to force the armature unit axially away from the pole core, the spring force of the spring element being chosen smaller than the holding force of the permanent magnet unit when the coil unit is not energized. The permanent magnet unit is stationarily arranged between a housing cover and the pole core, the armature plunger is rotationally arranged, and the spring element is supported on a part of the armature unit which is rotationally fixedly mounted.