To machine a single crystal with superior cutting faces and a small cutting loss in a cutting method for cutting the silicon single crystal by using laser machining.

In a cutting method of single crystal, a gas containing gaseous molecules or radicals which form stable gaseous molecules through reaction with the constituent atoms of the single crystal is used. While feeding the gas to the vicinity of the cutting part through a nozzle 304, the single crystal is cut by irradiating 301 the cutting part with ultra-short pulsed laser beams.