Provided are a physical condition management device and a method thereof capable of performing the early detection of the metabolic disease, a nutritional guidance, and a physical condition management diagnosis. The physical condition management device includes: an irradiation unit configured to radiate light at a predetermined light intensity toward an inside of a living body from an outside of the living body； a light intensity detection unit configured to detect a light intensity emitted from the living body, the light intensity detection unit being arranged at a predetermined interval from a light irradiation position of the irradiation unit； a scattering coefficient calculation unit configured to calculate a scattering coefficient of light inside the living body on the basis of the light intensity detected by the light intensity detection unit； a particle diameter calculation unit configured to calculate a variation of an average particle diameter of a lipid in blood on the basis of a variation of the scattering coefficient； and a physical condition determination unit configured to determine a physical condition from a temporal change in the variation of the average particle diameter.
