A light signalling device having 3-D optical effect. The device has a reflector 10 with a reflecting surface and a screen 7 arranged opposite the reflector and having a semi-reflecting zone. The screen being arranged away from the reflector and forming a cavity 5 with the reflector. The light rays of the source penetrate the cavity; and some of these rays are transmitted by the semi-reflecting zone, and others of these rays are reflected by the semi-reflecting zone, then by the reflector into the cavity in such a way as to generate a repetitive visual or three-dimensional effect of depth. The screen 7 is configured and arranged in relation to the direction of emission of the light source in such a way that another part of the light rays leaves the cavity at the level of the screen without meeting the semi-reflecting zone.