A protease was purified from the sarcocarp of Yubari melon fruit, the raw material used in the production of melon wine, by a series of treatments consisting of ammonium sulfate precipitation, gel filtration and ion-exchange chromatography. The enzyme was a monomer protein without a carbohydrate moiety. Its characteristics are as follws: molecular weight 66 kDa, isoelectric point pH 8.5, optimal temperature 40°C, and enzyme activity is promoted in the presence of Mn²⁺. It is a characterisric serine protease and preferentially hydrolyzes peptide bonds on the carboxyl terminal side of Phe and Arg. The sequence of the N termcnal 20 amcno acods was determined.