A cutter wheel for scribing a fragile material substrate having excellent biting in the surface of the fragile material substrate when the fragile material substrate used for a liquid crystal panel is cut and a method of manufacturing the cutter wheel with high productivity, a manual scribing tool, and a scribing device. The cutter wheel formed of a cemented carbide or a sintered diamond is so formed that a V-shaped ridge line part is formed as an edge along the circumferential part of a disk-like wheel, and at least one cutout is engraved in all the periphery of the ridge line part at pitches exceeding 200 [mu]m.