PURPOSE: To obtain a milk fraction useful as a medicine for enhancing oxidation resistance, having radical scavenger activity or a medicine for suppressing inflammation of skin caused by superoxide.

CONSTITUTION: A milk fraction contains <5%(wt.) of a saccharide component, has 1,700±500 Dalton molecular weight measured by gel filtration method and radical scavenger activity. A medicine contains the milk fraction as an active ingredient. The milk fraction is produced by de-fatting mammalian milk, ultrafiltering the de-fatted milk to collect a fraction having ≤10,000 Dalton molecular weight, purifying the collection fraction by a purifying means such as column chromatography or high performance chromatography to collect a fraction having 1,700±500 Dalton molecular weight. Since a large amount of the milk fraction can be prepared from a low-molecular weight fraction which has not been much utilized, this production has merits of effectively using resources.