Effects of a freezing period and frozen storage temperature on lipid oxidation of frozen Atlantic mackerel (Scomber scombrus Linnaeus) and frozen Chub mackerel (Scomber japonicus Houttuyn) during frozen storage were investigated. The lipids contents of frozen Atlantic mackerel captured from Norway and frozen Chub mackerel captured from low latitude of the sea near Japan in winter were higher than the other mackerel. Peroxide value and aldehyde contents increased by higher frozen temperature and storage period. In addition, 4-hydroxy-2-hexenal, one of the aldehyde generated by oxidation of n-3 unsaturated fatty acid, increased with the reduction of the vitamin E level during frozen storage. In this summary, the lipid oxidation of the frozen Atlantic and Chub mackerel in Japanese market were shown various levels. In order to improve these qualities from the point of view lipid oxidation, we needs to pay attention to temperature and period during the frozen storage.