Abstract: A method for decreasing a seed storage protein in seeds by a genetic engineering method and a method for transforming plants are disclosed. In the method of the present invention, a gene which is a template of a mRNA having a nucleotide sequence complementary to the mRNA of the seed storage protein is introduced in a plant; and the gene in seeds of the plant is transcribed to inhibit translation of the mRNA of the seed storage protein, thereby decreasing the seed storage protein in the seeds. In the method for transforming plants according to the present invention, a plant is transformed with a vector containing a glutelin promoter and a foreign gene.