The present invention relates to a crystals of glutathione trisulfide dihydrate and a method for producing the same. According to the present invention, for example, by concentrating a solution in which glutathione trisulfide is dissolved and then harvesting crystals of the precipitated glutathione trisulfide dihydrate, such crystals can be provided. The present invention also relates to a simple method for producing polysulfide in an aqueous solvent where hydrogen sulfide is not used but thiosulfate is used, the polysulfide being produced by agitating or leaving to stand a solution in which a compound having a thiol group or a disulfide bond and a thiosulfate are dissolved.
