The hard carbon is attractive for the Li ion battery because of its higher capacity than the theoretical value of 372Ahkg−1 based on the composition of stage 1 Li-intercalated graphite, LiC6. However, since the Li-doping reaction occurs at the potential of around 0V versus Li/Li+ reference electrode, it is often pointed out the possibility of Li metal deposition on the surface of anode. From the viewpoint of the safety, it may be a moot point. In the present study, 7Li NMR measurement was performed to estimate the degree of Li metal deposition on the surface of graphite and hard carbon anode. As a result, it is clarified that the Li metal deposition does not occur up to 110% over-discharge of the reversible capacity of hard carbon, whereas in the case of graphite anode, Li metal deposition occurred above 105% over-discharge of the capacity. From the 7Li NMR spectroscopy, the safety limit of hard carbon is rather superior to that of graphite.