Disclosed is a cargo container having an audio system, which is capable of broadcasting music and safety regulations for workers when they load or unload freight in or from the cargo container. An audio system is fixed to an inner surface of a corrugated wall of the cargo container. The audio system becomes operated so as to broadcast a radio station when a door of the cargo container is opened. The audio system has a sensor which detects the opening of the door, an automatic power supply switch which automatically supplies electric power from the battery to a printed circuit board when the opening of the door is detected by the sensor, a voice chip which reproduces voice data stored in it when the electric power is supplies through the automatic power supply switch, an a radio signal receiving section which is turned on and receives a radio broadcast signal when data reproductions by the voice chip is completed.