The present invention provides a means which can inhibit release of I2 in production or storage of 1,3-diiodohydantoin compound, and thereby solve decrease in purity of the compound and various problems caused by I2.The present invention provides a production method for 1,3-diiodohydantoin compound comprising a step to prepare a wet body containing a 1,3-diiodohydantoin compound, and (1) a step to dry the wet body by contacting the wet body with heated gas or (2) a step to lyophilize the wet body, a storage method for 1,3-diiodohydantoin compound comprising a step to store a 1,3-diiodohydantoin compound under a temperature condition of 15° C. or lower, and a 1,3-diiodohydantoin compound wherein content of released I2 is 1% by mass or less.