A lubricant including an ionic liquid, which includes a conjugate acid (B+) and a conjugate base (X−), and is protic, wherein the ionic liquid is represented by the following general formula (1): where R1 and R2 each represent a hydrogen atom or R1 and R2 form a benzene ring together with carbon atoms to which R1 and R2 are bonded, and R3 represents a straight-chain hydrocarbon group having 10 or more carbon atoms in the general formula (1).