A method and device for analyzing deformation of a secondary battery having an electrode assembly with a tab received in a case, the deformation analysis method including obtaining a first image by performing computed tomography (CT) imaging on the secondary battery, calculating a first position of the tab from the first image, obtaining a number of charge and discharge cycles of the secondary battery after charging and discharging the secondary battery multiple times so that the secondary battery deteriorates, obtaining a second image by performing CT imaging on the secondary battery deteriorated, calculating a second position of the tab from the second image and determining that the electrode assembly is deformed if an amount of change between the first position and the second position is greater than a reference value.