A light projecting apparatus of a scanner module, including: a substrate, a plurality of light emitting diodes (LEDs), positioned on the substrate and adapted to generate a plurality of incident beams; a diffusion plate, corresponding to the plurality of LEDs, adapted to receive the plurality of incident beams and diffuse the plurality of incident beams uniformly over a scanned object and including: a first plane, receiving the plurality of incident beams; two end faces; connected to the two ends of the first plane in a transverse direction; and a second plane, the two ends thereof being respectively connected to the two end faces, adapted to diffuse the plurality of incident beams uniformly over the scanned object and including: a plurality of second transverse concave portions, adapted to diffuse the plurality of incident beams; and a plurality of second transverse convex portions, adapted to gather the plurality of incident beams, where the plurality of second transverse convex portions and the plurality of second transverse concave portions are interlaced in a transverse direction, allowing the plurality of incident beams to be diffused uniformly over the scanned object.