A proposition of the present invention is to acquire necessary data without any chasm in an observation of a specimen containing plural kinds of substances of which exciting wavelengths are different. Accordingly, a spectral observation method of the present invention, irradiating light to the specimen containing plural kinds of substances (RFP, GFP, and so on) of which exciting wavelengths are different, and detecting spectra of light emitted from the specimen, the spectral observation method sequentially acquires spectral data of substances from the one of which exciting wavelength is long while switching a wavelength of the irradiated light among respective exciting wavelengths of the plural kinds of substances, and excludes the exciting wavelength of the substance corresponding to the spectral data to be acquired from detection wavelengths of the spectra each when acquiring the spectral data of the spectral data of the respective substances.