Abstract: The object of the present invention is to provide a method which provides a diaminobiphenyl compound in a high yield and in a short period of time by a benzidine rearrangement reaction of a hydrazobenzene having a bulky substituent group at the meta position. Specifically, the present invention provides a method for preparing a diaminobiphenyl compound represented by the following formula (1): wherein, X1 and X2 are, independently of each other, a group selected from the group consisting of a trifluoromethyl group and, optionally fluorinated, isopropyl, isobutyl, sec-butyl, tert-butyl and neopentyl groups, comprising a step of subjecting a diphenylhydrazine compound represented by the following formula (2) wherein X1 and X2 are as defined above, to a benzidine rearrangement reaction in the presence of an organic solvent and an inorganic acid at a temperature of from ?70° C. to ?11° C. to obtain the diaminobiphenyl compound represented by the formula (1).