The present invention provides a method for leak testing by which occurrence of fine leakage from a work as a test object can be determined without being affected by a released tracer gas that is also released from a non-defective work. The method for leak testing includes a series of steps including a gas bombing step wherein a work W as a test object is soaked in a pressurized tracer gas, a work setting step wherein the work subjected to the gas bombing is set in a hermetically sealed container 10, a vacuum suctioning step wherein the hermetically sealed container 10 is vacuum suctioned by a suction device 20 and a measuring step wherein tracer gas measurement data are obtained by measuring a vacuum suctioned tracer gas with a detector 30. Tracer gas measurement data for a non-defective work are preliminarily obtained by performing the series of steps for the non-defective work having same specifications as the work W as the test object. The tracer gas measurement data for the work W as the test object are compared with the tracer gas measurement data for the non-defective work in the measuring step, and thereby, occurrence of fine leakage from the work as the test object is determined.