The object of the invention is to provide a method for detecting an oxidation/reduction reaction of a molecule in a lipophilic portion and visualizing the reaction. This is a method for detecting an oxidation/reduction reaction of a molecule that undergoes a free-radical reaction in a lipid environment, the method including: a step in which a magnetic resonance method is applied to a living body or sample to be examined and a proton image of the molecule that undergoes a free-radical reaction in a lipid environment is thereby obtained and a step in which the proton image is examined for the image intensity of the living body or sample.
