A lubricant for use in an image forming apparatus, which contains a lubricant material and at least one of diamine compounds represented by chemical structure 1, 2, and 3, where R1 and R2 independently represent an alkyl group optionally having a substitution group and an aromatic hydrocarbon group optionally having a substitution group, one of R1 and R2 is an aromatic hydrocarbon group optionally having a substitution group, R1 and R2 optionally share bond connectivity to form a heterocyclic ring containing a nitrogen atom, and Ar represents an aromatic hydrocarbon group optionally having a substitution group, where R3 and R4 independently represent an alkyl group having one to four carbon atoms optionally substituted by an aromatic hydrocarbon group, R3 and R4 optionally share bond connectivity to form a heterocyclic ring containing a nitrogen atom, Ar1 and Ar2 independently represent a substituted or a non-substituted aromatic ring group, l and m each, independently, represent an integer of from 0 to 3 except that both l and m are zero at the same time, and n represents 1 or 2.