Abstract: A method and device for checking a joint of an electronic component is arranged to apply heat energy to a joint containing a heat conductive material and receive the infrared ray radiated from said joint with an infrared camera. By processing the image information output from the infrared camera, the method and device can offer an area of a defect, an area ratio of a defect, pixel coordinates, a temperature distribution pattern, a distance between central axes of a particular portion of the joint, or a gradient angle. The obtained value is compared with a predetermined value for determining the kind of a defect and whether or not the joint is defective.