The invention relates to a lighting and/or signalling device for a motor vehicle for lighting in a longitudinal emission direction. The lighting and/or signalling device has: at least one light source emitting light rays; and at least one light guiding sheet in which the light rays issuing from the light source spread by successive reflections, such that the guide sheet comprises at one end a reflective layer so as to redirect the light rays into the at least one sheet, and in that an output contour the sheet, at the end remote from the reflective layer, comprises a reflective profile, in particular inclined relative to the longitudinal axis of said sheet, so as to reflect the light rays reflected generally in an emission direction which is substantially parallel to said longitudinal axis.