A high frequency semiconductor device includes semiconductor elements provided on a semiconductor substrate, a surface insulating layer for covering the semiconductor elements, at least one wiring layer which is provided above the surface insulating layer, with at least one insulating interlayer provided therebetween, and which combines with the ground potential to form transmission line, and at least one heat-radiating stud which is provided in at least one throughhole so as to penetrate said insulating interlayers and so as not to penetrate said surface insulating layer.