Provided are a leakage inspection apparatus and a leakage inspection method for inspecting the flow rate of leakage from a tested body disposed in a tested-body chamber 21. The leakage inspection apparatus includes liquid supplying and pressurizing means 11 for supplying a probe liquid to the inside of the tested-body chamber 21 and pressurizing the probe liquid to a high pressure 0.1 MPa or more, vacuum evacuation means 22-b, 23-b and a quadrupole mass spectrometer 34. The tested body 21 is evacuated, the probe liquid is supplied to the inside of the tested body and pressurized to 0.1 MPa or more and the concentration of a probe medium leaked from the tested body and evaporated in a vacuum is measured by the quadrupole mass spectrometer 34, thereby measuring the flow rate of leakage from the tested body. This makes it possible to determine the flow rate of leakage using a liquid as a probe medium and simultaneously possible to perform a pressure tightness inspection at an atmospheric pressure of 0.1 MPa or more, especially at a high pressure ranging from 1 MPa to 1 GPa.