1. A lighting system for pellet analysis, comprising: a casing having an internal space, a through-hole formed at an upper side thereof, and inner upper and lower portions between which objects to be sorted comprising a plurality of pellets move; upper illumination assemblies, each of which comprises a plurality of first illumination sources irradiating first illumination light and a first light source holder fixing the first illumination sources onto an imaginary curved plane convexly rounded toward the objects in a circular arc direction corresponding to the vertical direction with respect to the casing such that rows of light source arrays, in which some of the plurality of first illumination sources are arrayed along the lengthwise direction of the imaginary curved plane, are arrayed parallel to the circular arc direction of the imaginary curved plane, arranged in the inner upper portion of the casing to irradiate the first illumination light toward upper and side portions of the objects; and lower illumination assemblies, each of which comprises a plurality of second illumination sources irradiating second illumination light and a second light source holder fixing the plurality of second illumination sources, arranged in the inner lower portion of the casing to irradiate the second illumination light toward lower and side portions of the objects.