An armrest for a motor vehicle, in particular a motor-vehicle side door armrest. In its general structure, the armrest has a stationary base part and a supporting part that is movable relative thereto, and additionally has a motor-driven adjusting device for the supporting part. The adjusting device comprises an electric motor and an eccentric that can be acted upon by the motor. The electric motor is configured as a component of a linear actuator connected to the eccentric.