To provide a method for reasonably purifying in high yield a p-quinone useful as an intermediate for pharmaceutical preparations.

This method comprises the steps of extracting a p-quinone of the general formula (I) from a mixture of the p-quinone of the general formula (I) and a diphenoquinone of the general formula (II) with a solvent and then purifying the p-quinone of the general formula (I); (wherein, in the formulas I and II, R1 to R4 are each H, a lower alkyl, lower alkenyl, aralkyl or aryl).