Manufacturing method of plate-shaped object

A manufacturing method of a plate-shaped object in which the plate-shaped object capable of being bent by an external force is manufactured by processing a plate-shaped workpiece formed of a hard material by a pulsed laser beam having such a wavelength as to be transmitted through the workpiece, the manufacturing method comprising:

• a shield tunnel forming step of forming, in the workpiece, a plurality of shield tunnels each including a pore formed along a thickness direction of the workpiece and a modified region that surrounds a lateral side of the pore, by irradiating the workpiece with the laser beam in a state in which a focal point of the laser beam is positioned to an inside of the workpiece;
• and
• an etching step of etching the plurality of shield tunnels by an etchant,
• wherein, in the shield tunnel forming step,
• a plurality of shield tunnels are formed in a first shield tunnel region that has a first length along a line-shaped first processing-planned region set on one surface of the workpiece, and
• a plurality of shield tunnels are formed in a second shield tunnel region that has a second length along a line-shaped second processing-planned region set in a region that is different from a region on an extension line of the first processing-planned region and is adjacent to the first processing-planned region on the one surface, and partly overlaps with the first shield tunnel region when the workpiece is viewed in a direction that goes from the first processing-planned region to the second processing-planned region.