A thin film transistor, a display device and a liquid crystal display device are provided. The thin film transistor includes a gate electrode film onto which light from a light source is irradiated, a semiconductor film formed on the gate electrode film and on an opposite side to the light source side through an insulating film, first and second electrode films formed to be in electrical contact with the semiconductor film, and a first shielding film formed in a same layer as the gate electrode film and electrically isolated from the gate electrode film, wherein the first shielding film overlaps a part of the semiconductor film as seen from the light irradiation direction and also overlaps at least a part of the first electrode film as seen from the light irradiation direction.