PURPOSE: To provide an electronic component mounting device which allows visual inspection of defects due to temperature increase of an electronic elements such as semiconductor.

CONSTITUTION: Photosensitive paper 19, which changes its color by temperature and does not return to the original color once it is changed, is adhered on the surface of the case of an electronic component mounting device (semiconductor) 18. How much the temperature of the electronic element mounting device 18 is increased can be judged by the color of the photosensitive paper 19 by comparing the color of the photosensitive paper with the corresponding temperature. Defect inspection is efficiently performed for the electronic component mounting device by visually inspecting the color of the photosensitive paper 19 adhered on the surface of the case.