A linear groove formation method comprising: coating a surface of a grain-oriented electrical steel sheet with a resist; performing a laser scan cyclically in a rolling direction of the grain-oriented electrical steel sheet, the laser scan being applying a laser while scanning the laser in a direction crossing the rolling direction of the grain-oriented electrical steel sheet to remove the resist in a portion irradiated with the laser; and etching the grain-oriented electrical steel sheet in each portion in which the resist is removed, to form a linear groove, wherein a coating thickness of the resist is 0.5 μm to 10 μm, a power of the laser is 1500 W or more, the laser scan is performed using one to five laser irradiation devices, a scanning time t per one laser scan is 2.5 msec or more, a ratio Y of a steel sheet scanning time t' during which the applied laser is actually scanned on the surface of the grain-oriented electrical steel sheet in one laser scan to the scanning time t per one laser scan is 0.8 or less, where Y = t'/t, and in case the laser scan is performed using one to three laser irradiation devices, a beam diameter of the laser in a direction orthogonal to a scanning direction of the laser is more than 0.1 mm and 0.4 mm or less, and a ratio of a major axis length to a minor axis length of the laser is 1.25 or less, and in case the laser scan is performed using four or five laser irradiation devices, a beam diameter of the laser in a direction orthogonal to a scanning direction of the laser is 0.03 mm or more and 0.1 mm or less, and a ratio of a major axis length to a minor axis length of the laser is 1.1 or less. coating a surface of a grain-oriented electrical steel sheet with a resist; performing a laser scan cyclically in a rolling direction of the grain-oriented electrical steel sheet, the laser scan being applying a laser while scanning the laser in a direction crossing the rolling direction of the grain-oriented electrical steel sheet to remove the resist in a portion irradiated with the laser; and etching the grain-oriented electrical steel sheet in each portion in which the resist is removed, to form a linear groove, wherein a coating thickness of the resist is 0.5 μm to 10 μm, a power of the laser is 1500 W or more, the laser scan is performed using one to five laser irradiation devices, a scanning time t per one laser scan is 2.5 msec or more, a ratio Y of a steel sheet scanning time t' during which the applied laser is actually scanned on the surface of the grain-oriented electrical steel sheet in one laser scan to the scanning time t per one laser scan is 0.8 or less, where Y = t'/t, and in case the laser scan is performed using one to three laser irradiation devices, a beam diameter of the laser in a direction orthogonal to a scanning direction of the laser is more than 0.1 mm and 0.4 mm or less, and a ratio of a major axis length to a minor axis length of the laser is 1.25 or less, and in case the laser scan is performed using four or five laser irradiation devices, a beam diameter of the laser in a direction orthogonal to a scanning direction of the laser is 0.03 mm or more and 0.1 mm or less, and a ratio of a major axis length to a minor axis length of the laser is 1.1 or less.