Provided is a method of separating a peptidoglycan-recognition protein from the hemolymph of Tenebrio molitor larvae, the method including: (a) preparing an affinity chromatography column by packing a column with a resin bound with at least one synthetic peptidoglycan; (b) applying the hemolymph of Tenebrio molitor larvae to the affinity chromatography column; (c) applying a mobile phase to the affinity chromatography column to obtain a peptidoglycan-recognition protein-containing solution eluted from the affinity chromatography column; and (d) purifying a peptidoglycan-recognition protein from the eluted solution.