To provide a method for easily and inexpensively producing a benzene carboxylic acid useful for a scale dispersing agent such as mellitic acid, without using dangerous chemicals such as a strong acid, with the use of a simple device.

This production method comprises anodizing a carbonaceous material having a six-membered ring structure of an anode in water, to form an aromatic carboxylic acid having one or more substituted carboxyl groups on a benzene ring.