The subject of the invention is a reflector device for a lighting module of a motor vehicle. The device includes a housing made of plastic, wherein the internal faces are metallized so as to reflect the light received. The housing on an external face of one of its walls has reception means able to house a support including at least one light source, the wall having an opening which leads toward the inside of the housing and which allows the light emitted by the light source or sources to propagate toward the inside of the housing. According to the provisions of the invention, the external face of the housing may be connected to ground potential so as to act as a shield against the electromagnetic waves emitted by various electronic components.