An ascorbic acid derivative, which is a compound represented by the following general formula (1) or a salt thereof: [Chemical Formula 11] (1)(wherein X and Y each represents H or a protective group for OH, R.sub.1 and R.sub.2 each represents an alkyl group having from 1 to 19 carbon atoms, which may be linear or branched, and the total number of carbon atoms in R.sub.1 R.sub.2 is an integer of 5 to 22).