Ascorbic acid solution was heated at 37℃ for 1 hour in the presence of Cu^<2+>, Fe^<2+>, Mn^<2+> and Zn^<2+> ions. Amounts of ascorbic acid remained after heating at pH 6.0 with 0.5% phytate, were 63.2,65.6 and 66.7% in the presence of Cu^<2+>, Fe^<2+>, plus Mn^<2+> and Zn^<2+>, respectively ; however without phytate the recoveries of ascorbic acid were 45.7,47.7 and 48.0%, respectively. In contrast to the experiment at pH 6.0,the protection of ascorbic acid was not observed at pH 3.0. From these results it is concluded that phytate inhibits the effect of metal ions on oxidative degradation of ascorbic acid only at neutral pH.