A scribing head 1 of this invention raises and lowers a scribing cutter by rotation of a servomotor 3. As a scribe pressure, a rotational torque of the servomotor 3 is transmitted to the scribing cutter. To form a scribe line across another scribe line which is formed earlier, the scribe pressure is raised temporarily when the scribing head passes the scribe line which is formed earlier. The rotational torque of the servomotor 3 is controlled at any of preset limits while the position of a cutter 6 of the scribing head shifts on the brittle substrate. The servomotor 3 is driven under position-control mode.