We would like to propose a muSR experiment on Li intercalated graphite, which is most commonly used for an anode material of Li-ion battery. With charging (discharging) reaction, Li is intercalated into (deintercalated from) graphite. In fully charged Li intercalated graphite, i.e., C6Li, Li locates between neighboring two sheets of graphene. This stracture is called Stage 1. C12Li has a stracture called Stage 2, where there are two layers of graphene between Li layer. In Li intercalated graphite CxLi with 6<x<12 Li, two phases, i.e., Stage 1 and Stage 2 co-exist. It is said that no Li-ion diffuses but the phase boundary moves with x. In order to know which is more reasonable explanation, Li-diffusion or movement of the phase boundary, we want to measurer muSR spectra on CxLi with two phases.