Presently provided are a cineraria-derived polynucleotide which can act as a promoter for a coding region of flavonoid 3′,5′-hydroxylase (F3′5′H and a F3′5′H gene construct which carries the polynucleotide. The cineraria-derived petal-specific promoter can be as polynucleotide having the nucleotide sequence depicted in SEQ ID NO: 9 or a polynucleotide which can hybridize with the polynucleotide having the nucleotide sequence depicted in SEQ ID NO: 9 under stringent conditions and can act as a promoter for a coding region of flavonoid. 3′,5′-hydroxylase (F3′5′H). The gene construct can be used, for inhibiting the expression of a gene in an RNAi method, which has, as a loop, a polynucleotide comprising the whole or a part of a first intron of the presently provided cineraria-derived polynucleotide.