The present disclosure relates to a decontamination method and apparatus for cladding hull wastes of spent nuclear fuels, capable of decontaminating a small quantity of spent nuclear fuels remaining on surfaces of the cladding hull wastes and radioactive fission products penetrated into the cladding hulls through an electrochemical dissolution. The method includes inserting the cladding hull waste into an anodic basket, immersing a reference electrode and a cathodic electrode as well as the anodic basket in a molten salt, dissolving a surface of the cladding hull waste by applying a voltage or current to the anodic basket with respect to the cathodic electrode or the reference electrode, removing the anodic basket, and removing a salt remaining on the surface of the cladding hull waste.