The present invention provides a method of manufacturing a highly pure ammonium succinate solution including the steps of (A) producing calcium succinate trihydrate by crystallization fermentation of a microorganism; (B) converting calcium succinate trihydrate to calcium succinate monohydrate by transition crystallization; (C) separating the calcium succinate monohydrate crystals; (D) substituting the calcium salt in the calcium succinate monohydrate with ammonium salt resulting in an ammonium succinate solution; and (E) removing the solid calcium carbonate from the ammonium succinate solution.