A thin film transistor includes a first insulating layer covering the gate electrode layer; source and drain regions which at least partly overlaps with the gate electrode layer; a pair of second insulating layers which is provided apart from each other in a channel length direction over the first insulating layer and which at least partly overlaps with the gate electrode layer and the pair of impurity semiconductor layers; a pair of microcrystalline semiconductor layers provided apart from each other on and in contact with the second insulating layers; and an amorphous semiconductor layer covering the first insulating layer, the pair of second insulating layers, and the pair of microcrystalline semiconductor layers and which extends to exist between the pair of microcrystalline semiconductor layers. The first insulating layer is a silicon nitride layer and each of the pair of the second insulating layers is a silicon oxynitride layer.