A light guide structure for a backlight module is provided. A light source of the backlight module emits a light beam. The light beam is guided by the light guide structure. The light guide structure includes a plate body and a light-shielding layer. The plate body includes a light-transmissible plate, a light-guiding plate and a reflecting plate. The light-guiding plate has a lateral surface. The light-transmissible plate has a light-transmissible plate lateral surface. The reflecting plate has a reflecting plate lateral surface. The lateral surface of the light-guiding plate, the light-transmissible plate lateral surface and the reflecting plate lateral surface are collaboratively formed as a plate body lateral surface. The plate body lateral surface is covered by the light-shielding layer. The light beam from the light source is blocked by the light-shielding layer.