An object of the present invention is to provide a red or orange fluorescent protein, which is characterized in that the difference (stokes shift) between an excitation peak value (wavelength of maximum absorption) and a fluorescence peak value (wavelength of maximum fluorescence) is greatened, so that the maximum fluorescence can be obtained by the maximum excitation. The present invention provides a novel fluorescent protein monomerized by introducing a mutation into a florescent protein derived from Fungia sp., and a novel chromoprotein and fluorescent protein derived from Montipora. sp.