A method for breaking an adhesive film mounted on the back of a wafer having a plurality of streets formed in a lattice pattern on the face of the wafer, and having devices formed in a plurality of regions demarcated by the plurality of streets, the devices being divided individually, is adapted to break the adhesive film along the outer peripheral edges of the individual devices, with the adhesive film being stuck to the surface of a dicing tape mounted on an annular frame. The method comprises: a laser processing step of projecting a laser beam with a pulse width of 100 picoseconds or less onto the adhesive film through gaps between the individually divided devices to form deteriorated layers in the adhesive film along the outer peripheral edges of the individual devices; and an adhesive film breaking step of exerting external force on the adhesive film having the deteriorated layers formed therein, to break the adhesive film along the deteriorated layers.