To provide a method for protecting a plant damage in chlorophyll, especially a damage caused by active oxygen, and to provide a plant body having such the protection mechanism.

The method comprises transducing an external metallothionine gene into a plant, in more detail, transducing the external metallothionine gene into the chlorophyll genome of the plant to impart oxidation stress resistance to the plant. A vector for transducing the external metallothionine gene into the plant is provided. A plant is transformed by transducing the external metallothionine gene. An anti-oxidizing agent contains the metallothionine originated from a plant.