An object of the present invention is to provide a reduced graphene-based material to improve charge/discharge efficiency of a lithium ion secondary battery. The reduced graphene-based material of the present invention has a coating containing lithium element (Li), phosphorus element (P), fluorine element (F), and oxygen element (O) on at least a part of the surface, wherein in the elemental composition of the surface as measured by X-ray photoelectron spectroscopy (XPS), the proportion of lithium element (Li) is 0.8 to 2.0 (atomic %), the proportion of phosphorus element (P) is 0.5 to 2.0 (atomic %), the proportion of fluorine element (F) is 0.05 to 1.0 (atomic %), and the proportion of oxygen element (O) is 7.0 to 12.0 (atomic %).