To provide a leakage detection method and device for accurately detecting the defect of the leakage part of an airtight test object.

An airtight test object 2 is dipped and arranged in inspection liquid W in a liquid storage tank 1 while an inner pressure is increased. In the inspection liquid W, a signal detection plate 3 that is formed by a pick-up part 3A facing the airtight test object 2 and a transmission plate 3B is arranged, and an AE sensor 5 is arranged at the transmission plate 3B, thus detecting liquid vibration being generated by air bubbles that are discharged from the detect part of the airtight test object 2 into the inspection liquid W using the pick-up part 3A, detecting solid vibration being propagated in the transmission plate 3B with the AE sensor 5, and outputting an AE signal to a processor S.