To provide a method for improving the adaptation ability of a plant to a high temperature by lowering the content of unsaturated fatty acid in the plant, and provide a high temperature resistant plant produced by the method.

The objective high temperature resistant plant is a transgenic plant produced by utilizing the gene of a chloroplast-localized fatty acid unsaturation gene and artificially lowering the expression of the gene by gene silencing technique. The produced plant has remarkably lowered triene fatty acid content in the biomembrane lipid, especially in the chloroplast membrane lipid. Although there is no difference in the growth between the objective plant and wild strain at normal growth temperature, the adaptation capability of the objective plant to high temperature is significantly increased at high temperature.