A method for dicing a substrate includes setting a target height for forming a first reforming region inside a target substrate, the target height being a distance from an upper surface of the target substrate to the first reforming region; irradiating a laser beam to a first sample substrate including a first film and a second film being in contact with the first film, and setting a target condition on the basis of a sample condition that results in forming a condensing point of the laser beam on an upper surface of the first film being in contact with the second film; and irradiating the target substrate with the laser beam according to the target condition to form the first reforming region inside the target substrate, wherein a thickness of the second film is the target height.