A laser welding device comprising: a laser scanner body configured to emit a laser beam to a workpiece; a jet nozzle (72a, 72b, 72c, 72d) configured to jet a gas from a first side to a second side so as to cause the gas to cross an optical path of the laser beam emitted from the laser scanner body; and a guide plate disposed on a downstream side in a flow direction of the gas, from the optical path of the laser beam, the guide plate being extended in a direction away from a laser irradiation position (Wo) on the workpiece toward the second side such that in use the flow direction of the gas that has crossed the optical path of the laser beam is changed into the direction away from the laser irradiation position (Wo) on the workpiece toward the downstream side and inclined at a predetermined inclination angle toward a direction opposite to the direction in which the laser beam is emitted in the flow direction of the gas; wherein a first end of the guide plate on an upstream side in the flow direction of the gas is continuously provided with an introduction plate disposed on the downstream side in the flow direction of the gas, from the optical path of the laser beam, the introduction plate being extended in a direction along the flow direction of the gas that has crossed the optical path of the laser beam, characterised in that: a surface of the introduction plate on the side of the introduction plate in the direction opposite to the direction in which the laser beam is emitted is slightly inclined toward the direction in which the laser beam is emitted, and in that a surface of the guide plate on the side of the guide plate in the direction opposite to the direction in which the laser beam is emitted is inclined at a predetermined inclination angle toward the direction opposite to the direction in which the laser beam is emitted as it goes toward the second side. a laser scanner body configured to emit a laser beam to a workpiece; a jet nozzle (72a, 72b, 72c, 72d) configured to jet a gas from a first side to a second side so as to cause the gas to cross an optical path of the laser beam emitted from the laser scanner body; and a guide plate disposed on a downstream side in a flow direction of the gas, from the optical path of the laser beam, the guide plate being extended in a direction away from a laser irradiation position (Wo) on the workpiece toward the second side such that in use the flow direction of the gas that has crossed the optical path of the laser beam is changed into the direction away from the laser irradiation position (Wo) on the workpiece toward the downstream side and inclined at a predetermined inclination angle toward a direction opposite to the direction in which the laser beam is emitted in the flow direction of the gas; wherein a first end of the guide plate on an upstream side in the flow direction of the gas is continuously provided with an introduction plate disposed on the downstream side in the flow direction of the gas, from the optical path of the laser beam, the introduction plate being extended in a direction along the flow direction of the gas that has crossed the optical path of the laser beam, characterised in that: a surface of the introduction plate on the side of the introduction plate in the direction opposite to the direction in which the laser beam is emitted is slightly inclined toward the direction in which the laser beam is emitted, and in that a surface of the guide plate on the side of the guide plate in the direction opposite to the direction in which the laser beam is emitted is inclined at a predetermined inclination angle toward the direction opposite to the direction in which the laser beam is emitted as it goes toward the second side. a surface of the introduction plate on the side of the introduction plate in the direction opposite to the direction in which the laser beam is emitted is slightly inclined toward the direction in which the laser beam is emitted, and in that a surface of the guide plate on the side of the guide plate in the direction opposite to the direction in which the laser beam is emitted is inclined at a predetermined inclination angle toward the direction opposite to the direction in which the laser beam is emitted as it goes toward the second side.