A lithium secondary battery, including: a hydrofluoric acid-containing electrolytic solution; an electrode; and a conductive assistant, in which the conductive assistant (1) contains a substance that is poorly soluble in the hydrofluoric acid-containing electrolytic solution, the substance including one or more kinds selected from transition metal compounds, and (2) contains a substance that is soluble in the hydrofluoric acid-containing electrolytic solution, the substance having a total metal mass of 0 mass % or more and 0.003 mass % or less with respect to a total mass of the electrode; and a conductive assistant, including: a substance that is poorly soluble in a hydrofluoric acid-containing electrolytic solution; and a substance that consumes hydrofluoric acid, the conductive assistant being substantially free, or including 1 mass % or less with respect to a total mass thereof, of a substance that is soluble in the hydrofluoric acid-containing electrolytic solution.