A light guiding plate and a light guiding device are provided, and the light guiding plate is implemented in the light guiding device. The light guiding device includes a side light source emitting light to the light guiding plate. The light guiding plate includes a first surface, a second surface and a third surface. The second surface is opposite to the first surface, and the third surface is adjacent to the first surface and the second surface. The second surface includes plural light guiding units, and each of the light guiding units includes a total reflection concavity and a light emitting convexity. The light emitting convexity surrounds the total reflection concavity.