An oil mist separator for separating aerosol oil from an oil-laden gas has an impactor. The impactor has a nozzle device with at least one nozzle for gas to be freed from oil, wherein the at least one nozzle has a streaming region. The impactor further has at least one deflector body having a separating region for the oil, wherein the separating region is positioned in the streaming region of the at least one nozzle. The separating region has a surface structure that is monolithically formed with the at least one deflector body. The surface structure has elevations and recesses arranged alternatingly in all directions transversely to a main streaming direction of the at least one nozzle.