Abstract: The prawn preservative of the invention includes an ascorbic acid compound at effective concentration and a reducing sugar compound in a ratio of 0.1-1 to the ascorbic acid compound contained. The method of preserving a prawn according to the invention includes subjecting a prawn maintained in a living state, in a raw state not undergoing apparent denaturation after death, or in a raw state not undergoing apparent denaturation after the thaw from a frozen state to treatment by dipping in the range of 0.3 to 5 minutes in a prawn preservation treatment solution consisting of an aqueous solution having an ascorbic acid compound at effective concentration and a reducing sugar compound in a ratio of 0.1-1 to the ascorbic acid compound contained, and then preserving the prawn under refrigeration or freezing.