A display device which has thin film transistors, wherein a semiconductor layer includes a first layer, second layers and third layers, the first layer has a channel region, the second layers are an impurity layer, the third layers are a low-concentration impurity layer, the second layers have connection portions connected with an electrodes, the third layers are formed to annularly surround the second layers, a channel-region-side edge portion out of edge portions of the third layer is in contact with the first layer, the edge portions of the third layer but the channel-region-side edge portion are in contact with an interlayer insulation film, the second layers have a first region where the second layer overlaps with a gate electrode and a second region where the second layer does not overlap with the gate electrode, and the connection portion is in the second region.