Abstract: Porphyran with modified bioactivity and physical property, method of making the modified Porphyran and use of modified Porphyran. Porphyran with modified bioactivity and physical property is produced by dissociating a salt from a sulphate group in Poryphran and removing it, making Porphyran having a free sulphate group wherein a salt is dissociated. Further, Porphyran with modified bioactivity and physical property is produced by dissociating a salt from sulphate group in Porphyran and removing it, and then altering the sulphate group, with the use of a given salt, into a sulphate salt of the given salt. The modified Porphyran also can be obtained by converting a salt of a sulphate group in Porphyran into a sulphate salt of a given salt by ion exchange. The modified Porphyran be added to cosmetics, food, and drink, and used as cosmetic, food and drink having inhibitory activity against hyaluronidase activity.