Cutting method and cutting stage of toughened glass

A cutting method of toughened glass which has been strengthened by having induced a compressive stress in a surface of a raw glass plate, the method comprising:

• reducing a tensile stress in an interior of a thickness of a cutting portion of a piece of toughened glass where a median crack is to be formed to a reduced stress having a maximum value within the thickness of the cutting portion of no greater than 20 MPa or any positive or negative value therebelow comprising concavely bending the piece of toughened glass such that the cutting portion becomes a trough;
• while the maximum value of the reduced stress within the thickness of the cutting portion where the median crack is to be formed remains at or below 20 MPa, scribing the piece of toughened glass from a surface of the cutting portion to a depth inside the interior of the thickness of the toughened piece of glass thereby forming the median crack, wherein the depth of the scribing is greater than a depth of layer from the surface of the cutting portion;
• and
• then breaking the scribed piece of toughened glass by expanding the median crack in the cutting portion of the toughened glass, comprising restoring the piece of toughened glass to a state less concavely bent than in the state in which the piece of toughened glass is scribed.