Abstract: In an arrangement for testing air-tightness of an electric device having an enclosed housing, and an electric connector fitted into an opening provided in the housing, the electric connector is provided with a communication hole for communicating the interior of the electric device with the exterior, and the communication hole is adapted to close when two halves of the connector are coupled with each other. Thus, the air-tightness of electric device can be conducted when the assembly work is substantially finished whereas the conventional arrangements require an additional assembly work step which could be a potential cause for loss of air tightness. Furthermore, the present invention can be implemented simply by providing a small communication hole in the electric connector and an associated sealing arrangement without requiring any change to the existing device to be tested.