The Oxidation of aflatoxin G₁(AFG₁) with ozone in chloroform solvent gave the stable ozonide into ozonization of the double bond in the terminal furan ring, and this reaction have been carried out for 3hr at -78.5℃. The chloroform solvent was removed in a stream of nitrogen and the residue was separated by elution chromatography (EC). The structure of this compound have been identified by using MS, ¹H-NMR, ^(13)C-NMR and I.R spectroscopy, respectively. This compound was formed the normal stable AFG₁-ozonide into spontaneous rearrangement after unstable ozonide according to sigmatropic rearrangement dependent upon cyclo addition by ozone.