The present invention relates to a sensor device for determining alignment/misalignment of a laser beam relative to a gas nozzle of a laser machining head which comprises a sensor housing provided with mounting means adapted to mount the housing to a laser machining head, a camera device comprising a camera, the camera device is provided in the sensor housing, so that the camera faces the tip of the gas nozzle when the sensor housing is mounted to the laser machining head for visualizing an orifice of the gas nozzle and a pilot laser simultaneously, and output means for outputting image signals obtained by the camera.