A method of ripping a plate material having a resilient part, a frame, and an easily breaking part formed between the resilient part and the frame includes holding the frame between an upper pad and a die on a first side of the easily breaking part, moving a punch toward a lower pad that is retractable against pushing force, to clamp the resilient part between the punch and the lower pad on a second side of the easily breaking part, and driving the punch so that the punch guides the plate material and applies tension to the easily breaking part in a surface direction of the plate material, thereby ripping the plate material along the easily breaking part. The method is capable of ripping the plate material without causing burrs.