PURPOSE: To make an automatic light extinction control device of a headlamp of an automobile compact, excellent in integrity, easy in installation and excellent in interference with stray light.

CONSTITUTION: A cylindrical cup shape housing 8 includes an elastic rubber pad 9, a thick film type control circuit chip 7, a light guiding sleeve 5, a photosensitive sensor 6, a convex lens 3 and a press ring 1. Additionally, the control circuit chip 7 makes contact with the rubber pad 9 provided on a cup bottom part of the housing and firmly connected to the photosensitive sensor 6 arranged at a central position of the bottom part of the light guiding sleeve 5, an outer edge part of the convex lens 3 is pressed by a peripheral part of the light guiding sleeve 5 and pressed by the press ring 1 integrated by press fitting engagement in an opening part of the housing 8, and a conductor 11 of the control circuit chip 7 is taken out through a housing wall.