This invention provides a process for preparing benzazepine compounds of the formula (1): wherein X1 is a halogen atom, R1 and R2 are a lower alkyl group, or salts thereof as well as intermediate benzoic acid compounds in high yield and high purity on industrial scale, which are useful as an intermediate for preparing a pharmaceutically active 2,3,4,5-tetrahydro-1H-1-benzazepine compound having vasopressin antagonistic activity.