Disclosed are a flame retardant polyurethane-urea hybrid coating agent composition containing expanded graphite and a method of preparing the same. More particularly, it relates to a flame retardant polyurethane-urea hybrid coating agent composition which is formed as a film on surfaces of coated structures, when coated on the interiors and exteriors of building structures, vessels, and marine structures, and, after the film formation, does not discharge toxic gases, particularly black smoke, and has a characteristic to self-extinguish within several seconds, in case of fire, and a method of manufacturing the same.