Conduction electron spin resonance (CESR) of alkali metal-graphite intercalation compounds (AM-GICs) such as KC8, KC24 , KC36 , RbC8 , RbC24 etc. and their ternary compounds with NH 3 was investigated. It was shown that ternary compound of RbC8 with ammonia gave a clear ESR signal, in contrast to no signal for binary RbC8 and that the line width of ESR spectra of KC8 (NH3 )(x) decreased monotonically with increasing ammonia content. These observations suggested that ammonia molecules reduce the spin-orbit interaction.