A light guide for a lighting and/or signaling device of an automobile vehicle comprising an entry face, a coupler, a main reflection face, and an exit face. The light guide is arranged in such a manner that, when a light source is disposed at a predetermined point with respect to the light guide, the entry face transmits the light from the light source to the coupler and the coupler transmits a part of this light to the main reflection face which directs it, in the form of a beam of parallel rays, directly or indirectly, toward the exit face in a direction forming an angle of 5° at the most with respect to the optical axis of the light guide.