<p>A novel fluorescent protein that is capable of controlling of fluorescence on and off by irradiation with two rays of different wavelengths. There is provided a fluorescent protein consisting of: (a) protein having an amino acid sequence of the SEQ ID NO: 3 or 7, or (b) protein having the same amino acid sequence as that of SEQ ID NO: 3 or 7 except for deletion, substitution and/or addition of one or two or more amino acid residues, the protein having fluorescence characteristics exhibiting photochromism effects.</p>
