The present invention relates to I- and II-type crystals of L-α-glyceryl phosphoryl choline, and to a method for preparing same. More particularly, the present invention relates to noble I- and II-type anhydride crystals of L-α-glyceryl phosphoryl choline, which have a higher purity than conventional liquid L-α-glyceryl phosphoryl choline, and one advantage of which is that formulations and dosages of pharmaceuticals are easily modified, and another advantage of which is that the hygroscopicity of the crystals are much lower than that of conventional polymorphic crystals, providing excellent stability during storage. The present invention also relates to a method for preparing the I- and II-type crystals of L-α-glyceryl phosphoryl choline. The I-type crystal of L-α-glyceryl phosphoryl choline is characterized by having an onset temperature of 147° C. and an absorption peak of 150° C. based on differential scanning calorimeter (DSC) analysis, and by having diffraction patterns where 2θ-diffraction angles are 9.8±0.2°, 12.0±0.2°, 14.3±0.2°, 15.8±0.2°, and 19.6±0.2° based on X-ray diffraction (XRD) analysis. The II-type crystal of L-α-glyceryl phosphoryl choline is characterized by having an onset temperature of 62° C. and an absorption peak of 66° C., and an onset temperature of 141° C. and an absorption peak of 145° C. based on DSC analysis, and having diffraction patterns where 2θ-diffraction angles are 10.3±0.2°, 12.2±0.2°, 13.4±0.2°, 14.8±0.2°, and 20.6±0.2° based on XRD analysis.