Provided are a method of full body cutting a brittle material without via the bend-breaking step, an apparatus of cutting a brittle material, a method of manufacturing a brittle material, and a cut brittle material. A method of cutting a brittle material, the method comprising: a conveyance cutting step of converging and irradiating an infrared ray to the brittle material linearly along a line using an infrared line heater while moving the infrared line heater relative to the brittle material in a direction along the line, thereby cutting the brittle material along the line.