The present invention provides a metal salt of 2-O-α-D- glycosyl-L-ascorbic acid represented by general formula (1), and amorphous powder there of and(wherein, n represents an integer above 1.)Further, the present invention provides an antioxidant comprising the metal salt of 2-O-α-D-glycosyl-L-ascorbic acid.本發明係提供通式(1)所示之2-O-α-D-糖基-L-抗壞血酸之金屬鹽及其非晶質粉末以及其製造方法。又,本發明係提供含有2-O-α-D-糖基-L-抗壞血酸之金屬鹽而成之抗氧化劑。(式中,n係表示1以上之整數)