A glass sheet processing method is provided for irradiating a laser beam on a glass sheet and forming a cleavage in the glass sheet with thermal stress. If each of an irradiation area of the laser beam on the surface and an irradiation area of the laser beam on the back face of the glass sheet includes a peak position of a power density of the laser beam, each irradiation area has an asymmetrical power density distribution that is asymmetrical with respect to a reference line that passes through the peak position and is parallel to a moving direction of the peak position. If each irradiation area has no peak position, each irradiation area has an asymmetrical shape that is asymmetrical with respect to a reference line that passes through a centroid position of the irradiation area and is parallel to a moving direction of the centroid position.