Inspection equipment specialized in leak detection using the bubble method. This device submerges test objects in a water tank and injects pressurized gas internally to visually or automatically detect bubbles generated from leak points. Applied to gross leak inspection of automotive parts, pipe fittings, containers, and electronic equipment housings, enabling identification and location of relatively large leaks. Unlike helium leak detectors or pressure decay methods, it features direct visual confirmation of leak points through bubble generation. Products include water tank bubble inspection equipment, automatic bubble detection systems, and air leak testers.