Disclosed is a gene having a novel function of increasing or decreasing the content of a protein in a seed.A chemric protein, which is a fusion of a transcription factor comprising a protein that comprises an amino acid sequence depicted in any one even-numbered sequence selected from SEQ ID NO:1 to SEQ ID NO:76 and a functional peptide capable of converting a transcription factor into a transcription inhibition factor, or a transcription factor, which comprises a protein that comprises an amino acid sequence depicted in any one even-numbered sequence selected from SEQ ID NO:77 to SEQ ID NO:84, is allowed to be expressed in a plant.