In a TFT including on the surface side of a substrate a channel region opposed to a gate electrode, with a gate insulating film provided therebetween, and a source-drain region connected to the channel region, and a TFT including a source-drain wiring layer electrically connected to the source-drain region, and a gate wiring layer electrically connected to the gate electrode, at least one component part composed of a conductive film or a semiconductor film, among the component parts of each TFT, is provided with a heat-radiating extension extended from the component part itself for enhancing the heat-radiating efficiency from the component part.