Elemental concentrations in hair (head and body hair) and dried serum have been measured by x-ray fluorescence analysis using synchrotron radiation. The relative concentration defined by log P-log S are obtained from the fluorescent spectra, where P is the peak height for the element and S is the background height. The observation shows that hair has two separate [Ca] concentration levels, the upper level and lower level. Since the content in hair growing at a steady state must be equal to the supply from serum, the upper and the lower level of hair [Ca] are attributed to open and close Ca ion channels of the hair matrix cells and can be derived from the serum concentrations of Ca ion and Ca atoms included in serum protein, respectively. The hair analysis is useful for cancer detection and protection as well as for diagnosing the Ca metabolism.