An object of the present invention is to provide a novel fluorescent protein derived from organisms other than Aequorea victoria. According to the present invention, there is provided a fluorescent protein derived from Fungia sp., which has the following properties: (1) the excitation maximum wavelength is 455 nm, and the fluorescence maximum wavelength is 488 nm; (2) the molar absorption coefficient at 455 nm is 38700 or 27700; (3) the quantum yield is 0.85 or 0.81; and (4) the pH sensitivity of the fluorescent property is stable at pH 5 to 9; and a fluorescent protein derived from Fungia sp., which has the following properties: (1) the excitation maximum wavelength is 548 nm, and the fluorescence maximum wavelength is 561 nm; (2) the molar absorption coefficient at 548 nm is 75900 or 51000; (3) the quantum yield is 0.44 or 0.50; and (4) the pH sensitivity of the fluorescent property is pKa<5.0.