PURPOSE: To obtain a novel aromatic diamine which is useful as a starting material for resins excellent in resistance to heat and chemicals, and in electric and mechanical characteristics, or as a hardening agent or a modifier.

CONSTITUTION: This aromatic diamine is expressed by formula I [Ri (i is 1-4) and Rj (j is 1-4) are each H, an alkyl, a cycloalkyl, an alkoxy, a halogen; Rm and Rn are each H, an alkyl, a halogenated alkyl, phenyl], for example, 1,1- bis[2-(4-aminophenoxy)-5-methylphenyl]methane. The aromatic diamine of formula I is prepared by condensation reaction between a bisphenol of formula II and a p-nitrohalobenzene followed by reduction of the corresponding aromatic dinitro compound. This new compound is useful as a starting chemical for resins, for example, a diisocyanate or a bismaleimide, a starting material for thermoplastic resins such as polyamide, polyimide or polyamideimide or a starting material for thermosetting resins such as epoxy resins.