PROBLEM TO BE SOLVED: To provide a differential pressure change amount calculation device capable of accurately calculating a differential pressure change amount caused by a leak from a sealed space.;SOLUTION: In leak inspection of a workpiece W, two leak inspections are performed at a time interval. On the basis of a first differential pressure change amount dPa1 and first workpiece temperature change amount dTw1 obtained in the first leak inspection and a second differential pressure change amount dPa2 and second workpiece temperature change amount dTw2 obtained in the second leak inspection, an actual differential pressure change amount dPa is calculated which is a time change amount of the differential pressure between the pressure of a sealed space WS and that of a comparison space CS, and is a time change amount of the differential pressure caused by a leak from the sealed space WS.;SELECTED DRAWING: Figure 2C;COPYRIGHT: (C)2017,JPO&INPIT
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