To clarify the lithium storage states in disordered carbon materials for Li-ion secondary batteries Li-nuclear magnetic resonance (NMR) spectra and cyclic voltammograms (CVs) of mesophase carbon fibers were measured, The CV obtained with mesophase carbon fibers fired at 800 degreesC showed two peaks positioned in different potential regions. A sharp peak appearing at about 0.03-0.2 V vs. Li/Li+ is attributed to lithium accommodation in the crystallites having a graphite structure and it broad one in the range of 0.2 to 1.2 V is attributed to the disorder site. In contrast, Li-7-NMR spectra of the 800 degreesC sample gave only it single peak. which shifted from 0 ppm at 0.8 V to 16 ppm at 30 mV depending on the charging level of lithium. Similar aspects of the spectra shift were also observed in a series of fully charged mesophase carbon fibers prepared at different firing temperatures. These results indicate that the rate of the exchange of lithium between the two different sites. the edge/surface site and intercalated site. is too fast to differentiate the different states. This suggests that there is a possibility of realizing it high capacity and high power anode for Li-ion secondary batteries based on a low-temperature mesophase carbon.