An object of the present invention is to provide a transgenic plant on which a useful phenotype is conferred by regulating expression of pseudo-response regulator (PRR) genes with an approach that is different from deletion of PRR genes. According to the present invention, there is provided a transgenic plant into which a polynucleotide encoding a protein comprising a CCT motif and a pseudo-receiver domain which is a common motif of plant pseudo-response regulator genes, a fusion polynucleotide of said polynucleotide and a polynucleotide encoding at least one transcription activation domain of a transcription factor, or a recombinant vector comprising said polynucleotide or fusion polynucleotide has been introduced.
