To provide a method for preparing 4-[3-(dibutylamino)propoxy]benzoyl derivative, useful as an intermediate of dronedarone.

The process for the preparation of 4-[3-(dibutylamino)propoxy]benzoyl chloride hydrochloride comprises (a) a step of producing a 1-4C alkyl-4-[3-(dibutylamino)propoxy] benzoate by reacting a 1-dibutylamino-3-chloropropane with a 1-4C alkyl-p-hydroxybenzoate in the presence of a base agent, (b) a step of forming a 4-[3-(dibutylamino)propoxy]benzoic acid hydrochloride by treating a salt formed by the saponification of the ester prepared in the above with a hydroxide of an alkali metal and then treating with hydrochloride, and (c) a step of forming the desired compound by treating the resultant hydrochloride salt with a chlorinating agent.