Resonance shift, K 125 , spin-lattice relaxation time, T 1 and spin–spin relaxation time, T 2 for 125 Te nuclei in molten Ge 15 Te 85 and Te in deeply under-cooled state have been measured as a function of temperature. The temperature dependence of K 125 is compared with that of the extent of structural change, C, and it is shown that the rapid increase of K 125 with increasing temperature can be attributed to an increase of the density of states at the Fermi level proportional to the extent of structural change. At high temperatures, the dependences on the temperature of K 125 and T 1 conform to the Korringa relation with an enhancement factor or the relaxation mechanism expected metallic nature. At low temperatures, in contrast, the Redfield theory assuming localized spins of which the density is proportional to C can explain the overall temperature dependences of T 1 and T 2 . These results provide the first clear evidence for a crossover transition from extended to localized states in the electron system accompanying the rapid structural changes.