To make it possible to objectively and exactly evaluate the degree of the chapping, etc., of the skin by irradiating the skin, etc., with UV light and measuring the waveform of the fluorescent band of the arom. amino acid in keratin having the fluorescence maximal near a specific wavelength, thereby evaluating the degree of chapping, etc., of the skin.

The front end of a probe 5 is pressed to the skin surface and the UV light from a light source 2 is introduced via a first optical cable section 4 and is irradiated toward the skin from the front end of the probe 5. The fluorescence derived from the arom. amino acid in the keratin forming the stratum corneum, etc., of the skin is then emitted. This fluorescence is condensed in a light condensing section 6 and is introduced via a second optical cable part to a spectral detecting section 8. The spectroscope 11 of this spectral detecting section 8 allows the transmission of the fluorescent band derived from the arom. amino acid in the keratin having the fluorescence maximal near 330nm and cuts the fluorescence of the wavelengths exclusive thereof. The fluorescence is detected by a photodetector 12 and is transduced to an electric signal which is sent to an information processing section 9. The relation between the wavelength and intensity of the fluorescence is thereby determined.