A mobile part of an electromagnetic actuator for an electric contactor. The mobile part is made up of a flat piece cut from a rolled sheet. This flat piece includes a first stage intended to face towards a fixed part of the actuator and a second stage, side-by-side with the first stage along an axis of movement of the mobile part. A solid section of the second stage, measured in a plane perpendicular to the axis of movement of the mobile part, is smaller than a solid section of the first stage.