New (2R,4R) monatin monosodium salt hydrate crystals characterized by having specific characteristic X-ray diffraction peaks provide general-purpose, stable, and safe monatin sodium salt crystals incorporating no organic solvent. These crystal may be prepared by a method that requires no organic solvent in the crystallization, separation, and drying steps. These crystal are useful as sweeteners and for the preparation of orally consumed products, such as foods, beverages, pharmaceutical products, topical pharmaceutical products, and feeds containing general-purpose, stable, and safe monatin sodium salt crystals.