A method for inspecting leakage of a container includes a differential pressure generation step of generating a differential pressure between the inside and the outside of a container; an ozone gas addition step of adding ozone gas to a higher pressure side of the inside and the outside; an ozone concentration detection step of measuring an ozone concentration of a lower pressure side of the inside and the outside; and a leakage determination step of determining presence of the leakage of the container based on a change in the ozone concentration.