Purine nucleotide derivative disodium crystals having a minimized amount of remaining alcohol such as methanol, ethanol or a mixture thereof are produced by overdrying purine nucleotide derivative disodium crystals containing the alcohol; and bringing the overdried purine nucleotide derivative disodium crystals into contact with an aqueous solution containing a hydrophilic organic solvent to control the humidity of the purine nucleotide derivative disodium crystals under a high humidity condition.