The present invention provides a sealed battery, in which leakage can be detected in reliable manner, a method for manufacturing the sealed battery, and a method for detecting leakage of the sealed battery. The invention provides a sealed battery containing helium, a method for manufacturing the sealed battery, and a method for detecting leakage. From inside a battery case sealed except an electrolyte inlet, the air is withdrawn, and pressure is applied by a gas containing helium under pressure higher than the atmospheric pressure through the electrolyte inlet. The electrolyte is injected, and after the electrolyte and the gas containing helium have been injected, the electrolyte inlet is sealed.