Phospholipids such as phosphatidylethanolamine and phosphatidylcholine play crucial roles in the biological system to maintain the cellular environmental condition. Despite that, oxidative stress targets these phospholipids containing polyunsaturated fatty acids and accompanies the oxidized phospholipids. Recent studies have been suggested that oxidized phospholipids have the relationship with inflammation and might induce the atherosclerosis formation by uptake of oxidized LDL through scavenger receptor as ligands. Red blood cells, which have been studied the bilayer model, are also modified by oxidative stress because hemoglobin can mediate and produce the reactive oxygen species, which leads to lipid peroxidation of biomembrane. In these oxidation processes of biomolecules, hexanoylation against phosphatidylethanolamine and phosphatidylserine, which has the primary amine and is the target of this modification, generates the oxidized membrane such as erythrocyte ghosts. This unique structure of phosphatidylethanolamine and phosphatidylserine is possibly the useful biomarker to evaluate the oxidation of biomembrane in vivo using liquid chromatography tandem mass spectrometry and monoclonal antibody.