A substituted benzoic acid derivative which is represented by the following formula (I) and has an NF-kappaB inhibiting action (in the formula, R 3 , R 4 and R 5 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon(s) or an alkoxy group having 1 to 6 carbon(s); R 9 and R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon(s) or an acyl group having 2 to 11 carbons); R 2 represents an optionally-substituted aromatic hydrocarbon group or an optionally-substituted heterocyclic group; and X represents a carboxyl group which may be esterified or amidated)